Surgical generator for ultrasonic and electrosurgical devices

ABSTRACT

In accordance with various embodiments, a surgical generator for providing a drive signal to a surgical device may comprise a first transformer and a second transformer. The first transformer may comprise a first primary winding and a first secondary winding. The second transformer may comprise a second primary winding and a second secondary winding. The surgical generator may further comprise a generator circuit to generate the drive signal. The generator circuit may be electrically coupled to the first primary winding to provide the drive signal across the first primary winding. The surgical generator may also comprise a patient-side circuit electrically isolated from the generator circuit. The patient-side circuit may be electrically coupled to the first secondary winding. Further, the patient-side circuit may comprise first and second output lines to provide the drive signal to the surgical device. In addition, the surgical generator may comprise a capacitor. The capacitor and the second secondary winding may be electrically coupled in series between the first output line and ground.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under Title 35, United States Code§119(e), of U.S. Provisional Patent Application Ser. No. 61/250,217,filed Oct. 9, 2009 and entitled A DUAL BIPOLAR AND ULTRASONIC GENERATORFOR ELECTRO-SURGICAL INSTRUMENTS, which is hereby incorporated byreference in its entirety.

The present application is related to the following, concurrently-filedU.S. patent applications, which are incorporated herein by reference intheir entirety:

(1) U.S. patent application Ser. No. ______, entitled DEVICES ANDTECHNIQUES FOR CUTTING AND COAGULATING TISSUE, Attorney Docket No.END6427USCIP1/080591CIP;

(2) U.S. patent application Ser. No. ______, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP/100558;

(3) U.S. patent application Ser. No. ______, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP2/100559;

(4) U.S. patent application Ser. No. ______, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP3/100560;

(5) U.S. patent application Ser. No. ______, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP4/100562;

(6) U.S. patent application Ser. No. ______, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP5/100563; and

(7) U.S. patent application Ser. No. ______, entitled SURGICAL GENERATORFOR ULTRASONIC AND ELECTROSURGICAL DEVICES, Attorney Docket No.END6673USNP6/100564.

BACKGROUND

Various embodiments are directed to surgical devices, and generators forsupplying energy to surgical devices, for use in open or minimallyinvasive surgical environments.

Ultrasonic surgical devices, such as ultrasonic scalpels, are findingincreasingly widespread applications in surgical procedures by virtue oftheir unique performance characteristics. Depending upon specific deviceconfigurations and operational parameters, ultrasonic surgical devicescan provide substantially simultaneous transection of tissue andhomeostasis by coagulation, desirably minimizing patient trauma. Anultrasonic surgical device may comprise a handpiece containing anultrasonic transducer, and an instrument coupled to the ultrasonictransducer having a distally-mounted end effector (e.g., a blade tip) tocut and seal tissue. In some cases, the instrument may be permanentlyaffixed to the handpiece. In other cases, the instrument may bedetachable from the handpiece, as in the case of a disposable instrumentor an instrument that is interchangeable between different handpieces.The end effector transmits ultrasonic energy to tissue brought intocontact with the end effector to realize cutting and sealing action.Ultrasonic surgical devices of this nature can be configured for opensurgical use, laparoscopic, or endoscopic surgical procedures includingrobotic-assisted procedures.

Ultrasonic energy cuts and coagulates tissue using temperatures lowerthan those used in electrosurgical procedures and can be transmitted tothe end effector by an ultrasonic generator in communication with thehandpiece. Vibrating at high frequencies (e.g., 55,500 times persecond), the ultrasonic blade denatures protein in the tissue to form asticky coagulum. Pressure exerted on tissue by the blade surfacecollapses blood vessels and allows the coagulum to form a haemostaticseal. A surgeon can control the cutting speed and coagulation by theforce applied to the tissue by the end effector, the time over which theforce is applied and the selected excursion level of the end effector.

The ultrasonic transducer may be modeled as an equivalent circuitcomprising first branch having a static capacitance and a second“motional” branch having a serially connected inductance, resistance andcapacitance that define the electromechanical properties of a resonator.Known ultrasonic generators may include a tuning inductor for tuning outthe static capacitance at a resonant frequency so that substantially allof generator's drive signal current flows into the motional branch.Accordingly, by using a tuning inductor, the generator's drive signalcurrent represents the motional branch current, and the generator isthus able to control its drive signal to maintain the ultrasonictransducer's resonant frequency. The tuning inductor may also transformthe phase impedance plot of the ultrasonic transducer to improve thegenerator's frequency lock capabilities. However, the tuning inductormust be matched with the specific static capacitance of an ultrasonictransducer at the operational resonance frequency. In other words, adifferent ultrasonic transducer having a different static capacitancerequires a different tuning inductor.

Additionally, in some ultrasonic generator architectures, thegenerator's drive signal exhibits asymmetrical harmonic distortion thatcomplicates impedance magnitude and phase measurements. For example, theaccuracy of impedance phase measurements may be reduced due to harmonicdistortion in the current and voltage signals.

Moreover, electromagnetic interference in noisy environments decreasesthe ability of the generator to maintain lock on the ultrasonictransducer's resonant frequency, increasing the likelihood of invalidcontrol algorithm inputs.

Electrosurgical devices for applying electrical energy to tissue inorder to treat and/or destroy the tissue are also finding increasinglywidespread applications in surgical procedures. An electrosurgicaldevice may comprise a handpiece and an instrument having adistally-mounted end effector (e.g., one or more electrodes). The endeffector can be positioned against the tissue such that electricalcurrent is introduced into the tissue. Electrosurgical devices can beconfigured for bipolar or monopolar operation. During bipolar operation,current is introduced into and returned from the tissue by active andreturn electrodes, respectively, of the end effector. During monopolaroperation, current is introduced into the tissue by an active electrodeof the end effector and returned through a return electrode (e.g., agrounding pad) separately located on a patient's body. Heat generated bythe current flow through the tissue may form haemostatic seals withinthe tissue and/or between tissues and thus may be particularly usefulfor sealing blood vessels, for example. The end effector of anelectrosurgical device may also comprise a cutting member that ismovable relative to the tissue and the electrodes to transect thetissue.

Electrical energy applied by an electrosurgical device can betransmitted to the instrument by a generator in communication with thehandpiece. The electrical energy may be in the form of radio frequency(“RF”) energy. RF energy is a form of electrical energy that may be inthe frequency range of 300 kHz to 1 MHz. During its operation, anelectrosurgical device can transmit low frequency RF energy throughtissue, which causes ionic agitation, or friction, in effect resistiveheating, thereby increasing the temperature of the tissue. Because asharp boundary may be created between the affected tissue and thesurrounding tissue, surgeons can operate with a high level of precisionand control, without sacrificing un-targeted adjacent tissue. The lowoperating temperatures of RF energy may be useful for removing,shrinking, or sculpting soft tissue while simultaneously sealing bloodvessels. RF energy may work particularly well on connective tissue,which is primarily comprised of collagen and shrinks when contacted byheat.

Due to their unique drive signal, sensing and feedback needs, ultrasonicand electrosurgical devices have generally required differentgenerators. Additionally, in cases where the instrument is disposable orinterchangeable with a handpiece, ultrasonic and electrosurgicalgenerators are limited in their ability to recognize the particularinstrument configuration being used and to optimize control anddiagnostic processes accordingly. Moreover, capacitive coupling betweenthe non-isolated and patient-isolated circuits of the generator,especially in cases where higher voltages and frequencies are used, mayresult in exposure of a patient to unacceptable levels of leakagecurrent.

SUMMARY

Various embodiments of a generator to communicate a drive signal to asurgical device are disclosed. In one embodiment, the generator maycomprise a power amplifier to receive a time-varying drive signalwaveform. The drive signal waveform may be generated by adigital-to-analog conversion of at least a portion of a plurality ofdrive signal waveform samples. An output of the power amplifier may befor generating a drive signal. The drive signal may comprise one of: afirst drive signal to be communicated to an ultrasonic surgical device,a second drive signal to be communicated to an electrosurgical device.The generator may also comprise a sampling circuit to generate samplesof current and voltage of the drive signal when the drive signal iscommunicated to the surgical device. Generation of the samples may besynchronized with the digital-to-analog conversion of the drive signalwaveform samples such that, for each digital-to-analog conversion of adrive signal waveform sample, the sampling circuit generates acorresponding set of current and voltage samples. The generator may alsocomprise at least one device programmed to, for each drive signalwaveform sample and corresponding set of current and voltage samples,store the current and voltage samples in a memory of the at least onedevice to associate the stored samples with the drive signal waveformsample. The at least one device may also be programmed to, when thedrive signal comprises the first drive signal: determine a motionalbranch current sample of the ultrasonic surgical device based on thestored current and voltage samples, compare the motional branch currentsample to a target sample selected from a plurality of target samplesthat define a target waveform, the target sample selected based on thedrive signal waveform sample, determine an amplitude error between thetarget sample and the motional branch current sample, and modify thedrive signal waveform sample such that an amplitude error determinedbetween the target sample and a subsequent motional branch currentsample based on current and voltage samples associated with the modifieddrive signal waveform sample is reduced.

In one embodiment, the generator may comprise a memory and a devicecoupled to the memory to receive for each of a plurality of drive signalwaveform samples used to synthesize the drive signal, a correspondingset of current and voltage samples of the drive signal. For each drivesignal waveform sample and corresponding set of current and voltagesamples, the device may store the samples in a memory of the device toassociate the stored samples with the drive signal waveform sample.Also, for each drive signal waveform sample and corresponding set ofcurrent and voltage samples, the device may, when the drive signalcomprises a first drive signal to be communicated to an ultrasonicsurgical device, determine a motional branch current sample of theultrasonic surgical device based on the stored samples, compare themotional branch current sample to a target sample selected from aplurality of target samples that define a target waveform, the targetsample selected based on the drive signal waveform sample, determine anamplitude error between the target sample and the motional branchcurrent sample, and modify the drive signal waveform sample such that anamplitude error determined between the target sample and a subsequentmotional branch current sample based on current and voltage samplesassociated with the modified drive signal waveform sample is reduced.

Embodiments of a method for determining motional branch current in anultrasonic transducer of an ultrasonic surgical device over multiplefrequencies of a transducer drive signal are also disclosed. In oneembodiment, the method may comprise, at each of a plurality offrequencies of the transducer drive signal, oversampling a current andvoltage of the transducer drive signal, receiving, by a processor, thecurrent and voltage samples, and determining, by the processor, themotional branch current based on the current and voltage samples, astatic capacitance of the ultrasonic transducer and the frequency of thetransducer drive signal.

Embodiments of a method for controlling a waveform shape of a motionalbranch current in an ultrasonic transducer of a surgical device are alsodisclosed. In one embodiment, the method may comprise generating atransducer drive signal by selectively recalling, using a direct digitalsynthesis (DDS) algorithm, drive signal waveform samples stored in alook-up table (LUT), generating samples of current and voltage of thetransducer drive signal when the transducer drive signal is communicatedto the surgical device, determining samples of the motional branchcurrent based on the current and voltage samples, a static capacitanceof the ultrasonic transducer and a frequency of the transducer drivesignal, comparing each sample of the motional branch current to arespective target sample of a target waveform to determine an erroramplitude, and modifying the drive signal waveform samples stored in theLUT such that an amplitude error between subsequent samples of themotional branch current and respective target samples is reduced.

In accordance with various embodiments, a surgical generator forproviding a drive signal to a surgical device may comprise a firsttransformer and a second transformer. The first transformer may comprisea first primary winding and a first secondary winding. The secondtransformer may comprise a second primary winding and a second secondarywinding. The surgical generator may further comprise a generator circuitto generate the drive signal. The generator circuit may be electricallycoupled to the first primary winding to provide the drive signal acrossthe first primary winding. The surgical generator may also comprise apatient-side circuit electrically isolated from the generator circuit.The patient-side circuit may be electrically coupled to the firstsecondary winding. Further, the patient-side circuit may comprise firstand second output lines to provide the drive signal to the surgicaldevice. In addition, the surgical generator may comprise a capacitor.The capacitor and the second secondary winding may be electricallycoupled in series between the first output line and ground.

Also, in accordance with various embodiments, a surgical generator forproviding a drive signal to a surgical device may comprise a firsttransformer, a patient-side circuit, and a capacitor. The firsttransformer may comprise a primary winding, a first secondary winding,and a second secondary winding. A polarity of the first secondarywinding relative to the primary winding may be opposite the polarity ofthe second secondary winding. The generator circuit may generate thedrive signal and may be electrically coupled to the first primarywinding to provide the drive signal across the first primary winding.The patient-side circuit may be electrically isolated from the generatorcircuit and may be electrically coupled to the first secondary winding.Also, the patient-side circuit may comprise first and second outputlines to provide the drive signal to the surgical device. The capacitorand second secondary winding may be electrically coupled in seriesbetween the first output line and ground.

Additionally, in accordance with various embodiments, a surgicalgenerator for providing a drive signal to a surgical device maycomprise, a first transformer, a generator circuit, a patient-sidecircuit and a capacitor. The first transformer may comprise a primarywinding and a secondary winding. The generator circuit may generate thedrive signal and may be electrically coupled to the first primarywinding to provide the drive signal across the first primary winding.The patient-side circuit may be electrically isolated from the generatorcircuit and may be electrically coupled to the secondary winding.Further, the patient-side circuit may comprise first and second outputlines to provide the drive signal to the surgical device. The capacitormay be electrically coupled to the primary winding and to the firstoutput line.

In accordance with various embodiments, a surgical generator forproviding a drive signal to a surgical device may comprise a firsttransformer, a generator circuit, a patient-side circuit, as well asfirst, second and third capacitors. The first transformer may comprise aprimary winding and a secondary winding. The generator circuit maygenerate the drive signal and may be electrically coupled to the firstprimary winding to provide the drive signal across the first primarywinding. The patient-side circuit may be electrically isolated from thegenerator circuit and may be electrically coupled to the secondarywinding. Further, the patient-side circuit may comprise first and secondoutput lines to provide the drive signal to the surgical device. A firstelectrode of the first capacitor may be electrically coupled to theprimary winding. A first electrode of the second capacitor may beelectrically coupled to the first output line and a second electrode ofthe second capacitor may be electrically coupled to a second electrodeof the first capacitor. A first electrode of the third capacitor may beelectrically coupled to the second electrode of the first capacitor andthe second electrode of the second capacitor. A second electrode of thethird capacitor may be electrically coupled to ground.

Various embodiments of surgical device control circuits are alsodisclosed. In one embodiment, the control circuit may comprise a firstcircuit portion comprising at least one first switch. The first circuitportion may communicate with a surgical generator over a conductor pair.The control circuit may also comprise a second circuit portioncomprising a data circuit element. The data circuit element may bedisposed in an instrument of the surgical device and transmit or receivedata. The data circuit element may implement data communications withthe surgical generator over at least one conductor of the conductorpair.

In one embodiment, the control circuit may comprise a first circuitportion comprising at least one first switch. The first circuit portionmay communicate with a surgical generator over a conductor pair. Thecontrol circuit may also comprise a second circuit portion comprising adata circuit element. The data circuit element may be disposed in aninstrument of the surgical device and transmit or receive data. The datacircuit element may implement data communications with the surgicalgenerator over at least one conductor of the conductor pair. The firstcircuit portion may receive a first interrogation signal transmittedfrom the surgical generator in a first frequency band. The data circuitelement may communicate with the surgical generator using anamplitude-modulated communication protocol transmitted in a secondfrequency band. The second frequency band may be higher than the firstfrequency band.

In one embodiment, the control circuit may comprise a first circuitportion comprising at least one first switch. The first circuit portionmay receive a first interrogation signal transmitted from a surgicalgenerator over a conductor pair. The control circuit may also comprise asecond circuit portion comprising at least one of a resistive elementand an inductive element disposed in an instrument of the device. Thesecond circuit portion may receive a second interrogation signaltransmitted from the surgical generator over the conductor pair. Thesecond circuit portion may be frequency-band separated from the firstcircuit portion. A characteristic of the first interrogation signal,when received through the first circuit portion, may be indicative of astate of the at least one first switch. A characteristic of the secondinterrogation signal, when received through the second circuit portion,may uniquely identify the instrument of the device.

In one embodiment, the control circuit may comprise a first circuitportion comprising a first switch network and a second switch network.The first switch network may comprise at least one first switch, and thesecond switch network may comprise at least one second switch. The firstcircuit portion may communicate with a surgical generator over aconductor pair. The control circuit may also comprise a second circuitportion comprising a data circuit element. The data circuit element maybe disposed in an instrument of the surgical device and may transmit orreceive data. The data circuit element may be in data communication withthe surgical generator over at least one conductor of the conductorpair.

In accordance with various embodiments, a surgical generator forproviding a drive signal to a surgical device may comprise a surgicalgenerator body having an aperture. The surgical generator may alsocomprise a receptacle assembly positioned in the aperture. Thereceptacle assembly may comprise a receptacle body and a flange havingan inner wall and an outer wall. The inner wall may be comprised of atleast one curved section and at least one linear section. The inner wallmay define a cavity. A central protruding portion may be positioned inthe cavity and may comprise a plurality of sockets and a magnet. Anouter periphery of the central protruding portion may comprise at leastone curved section and at least one linear section.

In accordance with various embodiments, a surgical instrument maycomprises an electrical connector assembly. The electrical connectorassembly may comprise a flange defining a central cavity and amagnetically compatible pin extending into the central cavity. Theelectrical connector assembly may comprise a circuit board and aplurality of electrically conductive pins coupled to the circuit board.Each of the plurality of electrically conductive pins may extending intothe central cavity. The electrical connector assembly may furthercomprise a strain relief member and a boot.

In accordance with various embodiments, a surgical instrument system maycomprise a surgical generator comprising a receptacle assembly. Thereceptacle assembly may comprise at least one curved section and atleast one linear portion. The surgical instrument system may comprise asurgical instrument comprising a connector assembly and an adapterassembly operatively coupled to the receptacle assembly and theconnector assembly. The adapter assembly may comprise a distal portioncontacting the receptacle assembly. The distal portion may comprise aflange with the flange having at least one curved section and at leastone linear portion. The adapter assembly may comprise a proximal portioncontacting the connector assembly. The proximal portion may define acavity dimensioned to receive at least a portion of the connectorassembly. The adapter assembly may further comprise a circuit board.

In accordance with various embodiments, methods may be utilized (e.g.,in conjunction with surgical instruments) to accomplish various surgicalobjectives. For example, methods to control electrical power provided totissue via first and second electrodes may comprise providing a drivesignal to the tissue via the first and second electrodes and modulatinga power provided to the tissue via the drive signal based on a sensedtissue impedance according to a first power curve. The first power curvemay define, for each of a plurality of potential sensed tissueimpedances, a first corresponding power. The methods may also comprisemonitoring a total energy provided to the tissue via the first andsecond electrodes. When the total energy reaches a first energythreshold, the methods may comprise determining whether an impedance ofthe tissue has reached a first impedance threshold. The methods mayfurther comprise, conditioned upon the impedance of the tissue failingto reach the first impedance threshold, modulating the power provided tothe tissue via the drive signal based on the sensed tissue impedanceaccording to a second power curve. The second power curve may define,for each of the plurality of potential sensed tissue impedances, asecond corresponding power.

In accordance with various embodiments, methods for controllingelectrical power provided to tissue via first and second electrodes maycomprise providing a drive signal to the tissue via the first and secondelectrodes and determining a power to be provided to the tissue. Thedetermining may comprise receiving an indication of a sensed tissueimpedance; determining a first corresponding power for the sensed tissueimpedance according to a power curve; and multiplying the correspondingpower by a multiplier. The power curve may define a corresponding powerfor each of a plurality of potential sensed tissue impedances. Themethods may further comprise modulating the drive signal to provide thedetermined power to the tissue and, conditioned upon the impedance ofthe tissue failing to reach a first impedance threshold, increasing themultiplier as a function of the total energy provided to the tissue.

In accordance with various embodiments, methods for controllingelectrical power provided to tissue via first and second electrodes maycomprise providing a drive signal to the tissue via the first and secondelectrodes and determining a power to be provided to the tissue. Thedetermining may comprise receiving an indication of a sensed tissueimpedance; determining a first corresponding power for the sensed tissueimpedance according to a power curve; and multiplying the correspondingpower by a first multiplier to find a determined power. The power curvemay define a corresponding power for each of a plurality of potentialsensed tissue impedances. The methods may further comprise modulatingthe drive signal to provide the determined power to the tissue andmonitoring a total energy provided to the tissue via the first andsecond electrodes. In addition, the methods may comprise, when the totalenergy reaches a first energy threshold, determining whether theimpedance of the tissue has reached a first impedance threshold; and,conditioned upon the impedance of the tissue not reaching the firstimpedance threshold, increasing the first multiplier by a first amount.

In accordance with various embodiments, methods for controllingelectrical power provided to tissue via a surgical device may compriseproviding a drive signal to a surgical device; receiving an indicationof an impedance of the tissue; calculating a rate of increase of theimpedance of the tissue; and modulating the drive signal to hold therate of increase of the impedance greater than or equal to apredetermined constant.

In accordance with various embodiments, methods for controllingelectrical power provided to tissue via a surgical device may compriseproviding a drive signal. A power of the drive signal may beproportional to a power provided to the tissue via the surgical device.The methods may also comprise periodically receiving indications of animpedance of the tissue and applying a first composite power curve tothe tissue, wherein applying the first composite power curve to thetissue comprises. Applying the first composite power curve to the tissuemay comprise modulating a first predetermined number of first compositepower curve pulses on the drive signal; and for each of the firstcomposite power curve pulses, determining a pulse power and a pulsewidth according to a first function of the impedance of the tissue Themethods may also comprise applying a second composite power curve to thetissue. Applying the second composite power curve to the tissue maycomprise modulating at least one second composite power curve pulse onthe drive signal; and for each of the at least one second compositepower curve pulses, determining a pulse power and a pulse widthaccording to a second function of the impedance of the tissue.

FIGURES

The novel features of the various embodiments are set forth withparticularity in the appended claims. The described embodiments,however, both as to organization and methods of operation, may be bestunderstood by reference to the following description, taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates one embodiment of a surgical system comprising agenerator and various surgical instruments usable therewith;

FIG. 2 illustrates one embodiment of an example ultrasonic device thatmay be used for transection and/or sealing;

FIG. 3 illustrates one embodiment of the end effector of the exampleultrasonic device of FIG. 2.

FIG. 4 illustrates one embodiment of an example electrosurgical devicethat may also be used for transection and sealing;

FIGS. 5, 6 and 7 illustrate one embodiment of the end effector shown inFIG. 4;

FIG. 8 is a diagram of the surgical system of FIG. 1;

FIG. 9 is a model illustrating motional branch current in oneembodiment;

FIG. 10 is a structural view of a generator architecture in oneembodiment;

FIGS. 11A-11C are functional views of a generator architecture in oneembodiment;

FIG. 12 illustrates a controller for monitoring input devices andcontrolling output devices in one embodiment;

FIG. 13 illustrates structural and functional aspects of one embodimentof the generator;

FIGS. 14-32 and 33A-33C illustrate embodiments of control circuits;

FIG. 33D-331 illustrate embodiments of cabling and adaptorconfigurations for connecting various generators and various surgicalinstruments;

FIG. 34 illustrates one embodiment of a circuit 300 for activecancellation of leakage current.

FIG. 35 illustrates one embodiment of a circuit that may be implementedby the generator of FIG. 1 to provide active cancellation of leakagecurrent;

FIG. 36 illustrates an alternative embodiment of a circuit that may beimplemented by the generator of FIG. 1 to provide active cancellation ofleakage current;

FIG. 37 illustrates an alternative embodiment of a circuit that may beimplemented by the generator of FIG. 1 to provide active cancellation ofleakage current;

FIG. 38 illustrates yet another embodiment of a circuit that may beimplemented by the generator of FIG. 1 to provide active cancellation ofleakage current;

FIG. 39 illustrates an embodiment of a circuit that may be implementedby the generator of FIG. 1 to provide cancellation of leakage current;

FIG. 40 illustrates another embodiment of a circuit that may beimplemented by the generator of FIG. 1 to provide cancellation ofleakage current;

FIG. 41 illustrates a receptacle and connector interface in oneembodiment;

FIG. 42 is an exploded side view of the receptacle assembly in oneembodiment;

FIG. 43 is an exploded side view of the connector assembly in oneembodiment;

FIG. 44 is a perspective view of the receptacle assembly shown in FIG.41;

FIG. 45 is a exploded perspective view of the receptacle assembly in oneembodiment;

FIG. 46 is a front elevation view of the receptacle assembly in oneembodiment;

FIG. 47 is a side elevation view of the receptacle assembly in oneembodiment;

FIG. 48 is an enlarged view of a socket in one embodiment;

FIG. 49 is a perspective view of the connector assembly in oneembodiment;

FIG. 50 is an exploded perspective view of the connector assembly in oneembodiment;

FIG. 51 is a side elevation view of a connector body in one embodiment;

FIG. 52 is perspective view of the distal end of a connector body in oneembodiment;

FIG. 53 is perspective view of the proximal end of a connector body inone embodiment;

FIG. 54 illustrates a ferrous pin in one embodiment;

FIG. 55 illustrates electrically conductive pins and a circuit board inone embodiment;

FIG. 56 illustrates a strain relief member in one embodiment;

FIG. 57 illustrates a boot in one embodiment;

FIG. 58 illustrates two adaptor assemblies in accordance with variousnon-limiting embodiments;

FIG. 59 illustrates a surgical generator in one embodiment;

FIG. 60 illustrates a connector assembly connected to an adaptorassembly in one embodiment;

FIG. 61 illustrates an adaptor assembly inserted into a receptacleassembly of a surgical generator in one embodiment;

FIG. 62 illustrates a connector assembly connected to an adaptorassembly in one embodiment;

FIG. 63 illustrates a perspective view of a back panel of a generator inone embodiment;

FIG. 64 illustrates a back panel of a generator in one embodiment;

FIGS. 65 and 66 illustrate different portions of a back panel of agenerator in one embodiment;

FIG. 67 illustrates a neural network for controlling a generator in oneembodiment;

FIG. 68 illustrates measured temperature versus estimated temperatureoutput by a surgical instrument controlled by a generator in oneembodiment;

FIG. 69 illustrates one embodiment of a chart showing example powercurves;

FIG. 70 illustrates one embodiment of a process flow for applying one ormore power curves to a tissue bite;

FIG. 71 illustrates one embodiment of a chart showing example powercurves that may be used in conjunction with the process flow of FIG. 70;

FIG. 72 illustrates one embodiment of a chart showing example commonshape power curves that may be used in conjunction with the process flowof FIG. 70;

FIG. 73A illustrates one embodiment of a routine that may be performedby a digital device of the generator of FIG. 1 to act upon a new tissuebite;

FIG. 73B illustrates one embodiment of a routine that may be performedby a digital device of the generator of FIG. 1 to monitor tissueimpedance;

FIG. 73C illustrates one embodiment of a routine that may be performedby a digital device of the generator of FIG. 1 to provide one or morepower curves to a tissue bite;

FIG. 74 illustrates one embodiment of a process flow for applying one ormore power curves to a tissue bite;

FIG. 75 illustrates one embodiment of a block diagram describing theselection and application of composite load curves by the generator ofFIG. 1;

FIG. 76 illustrates shows a process flow illustrating one embodiment ofthe algorithm of FIG. 75, as implemented by the generator of FIG. 1;

FIG. 77 illustrates one embodiment of a process flow for generating afirst composite load curve pulse;

FIG. 78 illustrates one embodiment of a pulse timing diagramillustrating an example application of the algorithm of FIG. 76 by thegenerator of FIG. 1;

FIG. 79 illustrates a graphical representation of drive signal voltage,current and power according to an example composite load curve;

FIGS. 80-85 illustrate a graphical representations of example compositeload curves; and

FIG. 86 illustrates one embodiment of a block diagram describing theapplication of an algorithm for maintaining a constant tissue impedancerate of change.

DESCRIPTION

Before explaining various embodiments of surgical devices and generatorsin detail, it should be noted that the illustrative embodiments are notlimited in application or use to the details of construction andarrangement of parts illustrated in the accompanying drawings anddescription. The illustrative embodiments may be implemented orincorporated in other embodiments, variations and modifications, and maybe practiced or carried out in various ways. Further, unless otherwiseindicated, the terms and expressions employed herein have been chosenfor the purpose of describing the illustrative embodiments for theconvenience of the reader and are not for the purpose of limitationthereof. Also, it will be appreciated that one or more of thefollowing-described embodiments, expressions of embodiments and/orexamples, can be combined with any one or more of the otherfollowing-described embodiments, expressions of embodiments and/orexamples.

Various embodiments are directed to improved ultrasonic surgicaldevices, electrosurgical devices and generators for use therewith.Embodiments of the ultrasonic surgical devices can be configured fortransecting and/or coagulating tissue during surgical procedures, forexample. Embodiments of the electrosurgical devices can be configuredfor transecting, coagulating, scaling, welding and/or desiccating tissueduring surgical procedures, for example.

Embodiments of the generator utilize high-speed analog-to-digitalsampling (e.g., approximately 200× oversampling, depending on frequency)of the generator drive signal current and voltage, along with digitalsignal processing, to provide a number of advantages and benefits overknown generator architectures. In one embodiment, for example, based oncurrent and voltage feedback data, a value of the ultrasonic transducerstatic capacitance, and a value of the drive signal frequency, thegenerator may determine the motional branch current of an ultrasonictransducer. This provides the benefit of a virtually tuned system, andsimulates the presence of a system that is tuned or resonant with anyvalue of the static capacitance (e.g., C₀ in FIG. 9) at any frequency.Accordingly, control of the motional branch current may be realized bytuning out the effects of the static capacitance without the need for atuning inductor. Additionally, the elimination of the tuning inductormay not degrade the generator's frequency lock capabilities, asfrequency lock can be realized by suitably processing the current andvoltage feedback data.

High-speed analog-to-digital sampling of the generator drive signalcurrent and voltage, along with digital signal processing, may alsoenable precise digital filtering of the samples. For example,embodiments of the generator may utilize a low-pass digital filter(e.g., a finite impulse response (FIR) filter) that rolls off between afundamental drive signal frequency and a second-order harmonic to reducethe asymmetrical harmonic distortion and EMI-induced noise in currentand voltage feedback samples. The filtered current and voltage feedbacksamples represent substantially the fundamental drive signal frequency,thus enabling a more accurate impedance phase measurement with respectto the fundamental drive signal frequency and an improvement in thegenerator's ability to maintain resonant frequency lock. The accuracy ofthe impedance phase measurement may be further enhanced by averagingfalling edge and rising edge phase measurements, and by regulating themeasured impedance phase to 0°.

Various embodiments of the generator may also utilize the high-speedanalog-to-digital sampling of the generator drive signal current andvoltage, along with digital signal processing, to determine real powerconsumption and other quantities with a high degree of precision. Thismay allow the generator to implement a number of useful algorithms, suchas, for example, controlling the amount of power delivered to tissue asthe impedance of the tissue changes and controlling the power deliveryto maintain a constant rate of tissue impedance increase.

Various embodiments of the generator may have a wide frequency range andincreased output power necessary to drive both ultrasonic surgicaldevices and electrosurgical devices. The lower voltage, higher currentdemand of electrosurgical devices may be met by a dedicated tap on awideband power transformer, thereby eliminating the need for a separatepower amplifier and output transformer. Moreover, sensing and feedbackcircuits of the generator may support a large dynamic range thataddresses the needs of both ultrasonic and electrosurgical applicationswith minimal distortion.

Various embodiments may provide a simple, economical means for thegenerator to read from, and optionally write to, data circuit (e.g., asingle-wire bus device, such as a 1-Wire® protocol EEPROM) disposed inan instrument attached to the handpiece using existing multi-conductorgenerator/handpiece cables. In this way, the generator is able toretrieve and process instrument-specific data from an instrumentattached to the handpiece. This may enable the generator to providebetter control and improved diagnostics and error detection.Additionally, the ability of the generator to write data to theinstrument makes possible new functionality in terms of, for example,tracking instrument usage and capturing operational data. Moreover, theuse of frequency band permits the backward compatibility of instrumentscontaining a bus device with existing generators.

Disclosed embodiments of the generator provide active cancellation ofleakage current caused by unintended capacitive coupling betweennon-isolated and patient-isolated circuits of the generator. In additionto reducing patient risk, the reduction of leakage current may alsolessen electromagnetic emissions.

These and other benefits of embodiments of the present invention will beapparent from the description to follow.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping a handpiece. Thus, an endeffector is distal with respect to the more proximal handpiece. It willbe further appreciated that, for convenience and clarity, spatial termssuch as “top” and “bottom” may also be used herein with respect to theclinician gripping the handpiece. However, surgical devices are used inmany orientations and positions, and these terms are not intended to belimiting and absolute.

FIG. 1 illustrates one embodiment of a surgical system 100 comprising agenerator 102 configurable for use with surgical devices. According tovarious embodiments, the generator 102 may be configurable for use withsurgical devices of different types, including, for example, theultrasonic surgical device 104 and electrosurgical or RF surgical device106. Although in the embodiment of FIG. 1 the generator 102 is shownseparate from the surgical devices 104, 106, in certain embodiments thegenerator 102 may be formed integrally with either of the surgicaldevices 104, 106 to form a unitary surgical system.

FIG. 2 illustrates one embodiment of an example ultrasonic device 104that may be used for transection and/or sealing. The device 104 maycomprise a hand piece 116 which may, in turn, comprise an ultrasonictransducer 114. The transducer 114 may be in electrical communicationwith the generator 102, for example, via a cable 122 (e.g., amulti-conductor cable). The transducer 114 may comprise piezoceramicelements, or other elements or components suitable for converting theelectrical energy of a drive signal into mechanical vibrations. Whenactivated by the generator 102, the ultrasonic transducer 114 may causelongitudinal vibration. The vibration may be transmitted through aninstrument portion 124 of the device 104 (e.g., via a waveguide embeddedin an outer sheath) to an end effector 126 of the instrument portion124.

FIG. 3 illustrates one embodiment of the end effector 126 of the exampleultrasonic device 104. The end effector 126 may comprise a blade 151that may be coupled to the ultrasonic transducer 114 via the wave guide(not shown). When driven by the transducer 114, the blade 151 mayvibrate and, when brought into contact with tissue, may cut and/orcoagulate the tissue, as described herein. According to variousembodiments, and as illustrated in FIG. 3, the end effector 126 may alsocomprise a clamp arm 155 that may be configured for cooperative actionwith the blade 151 of the end effector 126. With the blade 151, theclamp arm 155 may comprise a set of jaws 140. The clamp arm 155 may bepivotally connected at a distal end of a shaft 153 of the instrumentportion 124. The clamp arm 155 may include a clamp arm tissue pad 163,which may be formed from TEFLON® or other suitable low-frictionmaterial. The pad 163 may be mounted for cooperation with the blade 151,with pivotal movement of the clamp arm 155 positioning the clamp pad 163in substantially parallel relationship to, and in contact with, theblade 151. By this construction, a tissue bite to be clamped may begrasped between the tissue pad 163 and the blade 151. The tissue pad 163may be provided with a sawtooth-like configuration including a pluralityof axially spaced, proximally extending gripping teeth 161 to enhancethe gripping of tissue in cooperation with the blade 151. The clamp arm155 may transition from the open position shown in FIG. 3 to a closedposition (with the clamp arm 155 in contact with or proximity to theblade 151) in any suitable manner. For example, the hand piece 116 maycomprise a jaw closure trigger 138. When actuated by a clinician, thejaw closure trigger 138 may pivot the clamp arm 155 in any suitablemanner.

The generator 102 may be activated to provide the drive signal to thetransducer 114 in any suitable manner. For example, the generator 102may comprise a foot switch 120 coupled to the generator 102 via afootswitch cable 122 (FIG. 8). A clinician may activate the transducer114, and thereby the transducer 114 and blade 151, by depressing thefoot switch 120. In addition, or instead of the foot switch 120 someembodiments of the device 104 may utilize one or more switchespositioned on the hand piece 116 that, when activated, may cause thegenerator 102 to activate the transducer 114. In one embodiment, forexample, the one or more switches may comprise a pair of toggle buttons136 a, 136 b, for example, to determine an operating mode of the device104. When the toggle button 136 a is depressed, for example, theultrasonic generator 102 may provide a maximum drive signal to thetransducer 114, causing it to produce maximum ultrasonic energy output.Depressing toggle button 136 b may cause the ultrasonic generator 102 toprovide a user-selectable drive signal to the transducer 114, causing itto produce less than the maximum ultrasonic energy output. The device104 additionally or alternatively may comprise a second switch to, forexample, indicate a position of a jaw closure trigger 138 for operatingjaws 140 of the end effector 126. Also, in some embodiments, theultrasonic generator 102 may be activated based on the position of thejaw closure trigger 138, (e.g., as the clinician depresses the jawclosure trigger 138 to close the jaws 140, ultrasonic energy may beapplied.

Additionally or alternatively, the one or more switches may comprises atoggle button 136 c that, when depressed, causes the generator 102 toprovide a pulsed output. The pulses may be provided at any suitablefrequency and grouping, for example. In certain embodiments, the powerlevel of the pulses may be the power levels associated with togglebuttons 136 a,b (maximum, less than maximum), for example.

It will be appreciated that a device 104 may comprise any combination ofthe toggle buttons 136 a,b,c. For example, the device 104 could beconfigured to have only two toggle buttons: a toggle button 136 a forproducing maximum ultrasonic energy output and a toggle button 136 c forproducing a pulsed output at either the maximum or less than maximumpower level per. In this way, the drive signal output configuration ofthe generator 102 could be 5 continuous signals and 5 or 4 or 3 or 2 or1 pulsed signals. In certain embodiments, the specific drive signalconfiguration may be controlled based upon, for example, EEPROM settingsin the generator 102 and/or user power level selection(s).

In certain embodiments, a two-position switch may be provided as analternative to a toggle button 136 c. For example, a device 104 mayinclude a toggle button 136 a for producing a continuous output at amaximum power level and a two-position toggle button 136 b. In a firstdetented position, toggle button 136 b may produce a continuous outputat a less than maximum power level, and in a second detented positionthe toggle button 136 b may produce a pulsed output (e.g., at either amaximum or less than maximum power level, depending upon the EEPROMsettings).

In some embodiments, the end effector 126 may also comprise a pair ofelectrodes 159, 157. The electrodes 159, 157 may be in communicationwith the generator 102, for example, via the cable 122. The electrodes159, 157 may be used, for example, to measure an impedance of a tissuebite present between the clamp arm 155 and the blade 151. The generator102 may provide a signal (e.g., a non-therapeutic signal) to theelectrodes 159, 157. The impedance of the tissue bite may be found, forexample, by monitoring the current, voltage, etc. of the signal.

FIG. 4 illustrates one embodiment of an example electrosurgical device106 that may also be used for transection and sealing. According tovarious embodiments, the transection and sealing device 106 may comprisea hand piece assembly 130, a shaft 165 and an end effector 132. Theshaft 165 may be rigid (e.g., for laparoscopic and/or open surgicalapplication) or flexible, as shown, (e.g., for endoscopic application).In various embodiments, the shaft 165 may comprise one or morearticulation points. The end effector 132 may comprise jaws 144 having afirst jaw member 167 and a second jaw member 169. The first jaw member167 and second jaw member 169 may be connected to a clevis 171, which,in turn, may be coupled to the shaft 165. A translating member 173 mayextend within the shaft 165 from the end effector 132 to the hand piece130. At the hand piece 130, the shaft 165 may be directly or indirectlycoupled to a jaw closure trigger 142 (FIG. 4).

The jaw members 167, 169 of the end effector 132 may comprise respectiveelectrodes 177, 179. The electrodes 177, 179 may be connected to thegenerator 102 via electrical leads 187 a, 187 b (FIG. 5) extending fromthe end effector 132 through the shaft 165 and hand piece 130 andultimately to the generator 102 (e.g., by a multiconductor cable 128).The generator 102 may provide a drive signal to the electrodes 177, 179to bring about a therapeutic effect to tissue present within the jawmembers 167, 169. The electrodes 177, 179 may comprise an activeelectrode and a return electrode, wherein the active electrode and thereturn electrode can be positioned against, or adjacent to, the tissueto be treated such that current can flow from the active electrode tothe return electrode through the tissue. As illustrated in FIG. 4, theend effector 132 is shown with the jaw members 167, 169 in an openposition. A reciprocating blade 175 is illustrated between the jawmembers 167, 169.

FIGS. 5, 6 and 7 illustrate one embodiment of the end effector 132 shownin FIG. 4. To close the jaws 144 of the end effector 132, a clinicianmay cause the jaw closure trigger 142 to pivot along arrow 183 from afirst position to a second position. This may cause the jaws 144 to openand close according to any suitable method. For example, motion of thejaw closure trigger 142 may, in turn, cause the translating member 173to translate within a bore 185 of the shaft 165. A distal portion of thetranslating member 173 may be coupled to a reciprocating member 197 suchthat distal and proximal motion of the translating member 173 causescorresponding distal and proximal motion of the reciprocating member.The reciprocating member 197 may have shoulder portions 191 a, 191 b,while the jaw members 167, 169 may have corresponding cam surfaces 189a, 189 b. As the reciprocating member 197 is translated distally fromthe position shown in FIG. 6 to the position shown in FIG. 7, theshoulder portions 191 a, 191 b may contact the cam surfaces 189 a, 189b, causing the jaw members 167, 169 to transition to the closedposition. Also, in various embodiments, the blade 175 may be positionedat a distal end of the reciprocating member 197. As the reciprocatingmember extends to the fully distal position shown in FIG. 7, the blade175 may be pushed through any tissue present between the jaw members167, 169, in the process, severing it.

In use, a clinician may place the end effector 132 and close the jaws144 around a tissue bite to be acted upon, for example, by pivoting thejaw closure trigger 142 along arrow 183 as described. Once the tissuebite is secure between the jaws 144, the clinician may initiate theprovision of RF or other electro-surgical energy by the generator 102and through the electrodes 177, 179. The provision of RF energy may beaccomplished in any suitable way. For example, the clinician mayactivate the foot switch 120 (FIG. 8) of the generator 102 to initiatethe provision of RF energy. Also, for example, the hand piece 130 maycomprise one or more switches 181 that may be actuated by the clinicianto cause the generator 102 to begin providing RF energy. Additionally,in some embodiments, RF energy may be provided based on the position ofthe jaw closure trigger 142. For example, when the trigger 142 is fullydepressed (indicating that the jaws 144 are closed), RF energy may beprovided. Also, according to various embodiments, the blade 175 may beadvanced during closure of the jaws 144 or may be separately advanced bythe clinician after closure of the jaws 144 (e.g., after a RF energy hasbeen applied to the tissue).

FIG. 8 is a diagram of the surgical system 100 of FIG. 1. In variousembodiments, the generator 102 may comprise several separate functionalelements, such as modules and/or blocks. Different functional elementsor modules may be configured for driving the different kinds of surgicaldevices 104, 106. For example an ultrasonic generator module 108 maydrive an ultrasonic device, such as the ultrasonic device 104. Anelectrosurgery/RF generator module 110 may drive the electrosurgicaldevice 106. For example, the respective modules 108, 110 may generaterespective drive signals for driving the surgical devices 104, 106. Invarious embodiments, the ultrasonic generator module 108 and/or theelectrosurgery/RF generator module 110 each may be formed integrallywith the generator 102. Alternatively, one or more of the modules 108,110 may be provided as a separate circuit module electrically coupled tothe generator 102. (The modules 108 and 110 are shown in phantom toillustrate this option.) Also, in some embodiments, theelectrosurgery/RF generator module 110 may be formed integrally with theultrasonic generator module 108, or vice versa.

In accordance with the described embodiments, the ultrasonic generatormodule 108 may produce a drive signal or signals of particular voltages,currents, and frequencies, e.g. 55,500 cycles per second (Hz). The drivesignal or signals may be provided to the ultrasonic device 104, andspecifically to the transducer 114, which may operate, for example, asdescribed above. In one embodiment, the generator 102 may be configuredto produce a drive signal of a particular voltage, current, and/orfrequency output signal that can be stepped with high resolution,accuracy, and repeatability.

In accordance with the described embodiments, the electrosurgery/RFgenerator module 110 may generate a drive signal or signals with outputpower sufficient to perform bipolar electrosurgery using radio frequency(RF) energy. In bipolar electrosurgery applications. The drive signalmay be provided, for example, to the electrodes 177, 179 of theelectrosurgical device 106, for example, as described above.Accordingly, the generator 102 may be configured for therapeuticpurposes by applying electrical energy to the tissue sufficient fortreating the tissue (e.g., coagulation, cauterization, tissue welding,etc.).

The generator 102 may comprise an input device 145 (FIG. 1) located, forexample, on a front panel of the generator 102 console. The input device145 may comprise any suitable device that generates signals suitable forprogramming the operation of the generator 102. In operation, the usercan program or otherwise control operation of the generator 102 usingthe input device 145. The input device 145 may comprise any suitabledevice that generates signals that can be used by the generator (e.g.,by one or more processors contained in the generator) to control theoperation of the generator 102 (e.g., operation of the ultrasonicgenerator module 108 and/or electrosurgery/RF generator module 110). Invarious embodiments, the input device 145 includes one or more ofbuttons, switches, thumbwheels, keyboard, keypad, touch screen monitor,pointing device, remote connection to a general purpose or dedicatedcomputer. In other embodiments, the input device 145 may comprise asuitable user interface, such as one or more user interface screensdisplayed on a touch screen monitor, for example. Accordingly, by way ofthe input device 145, the user can set or program various operatingparameters of the generator, such as, for example, current (I), voltage(V), frequency (f), and/or period (T) of a drive signal or signalsgenerated by the ultrasonic generator module 108 and/orelectrosurgery/RF generator module 110.

The generator 102 may also comprise an output device 147 (FIG. 1)located, for example, on a front panel of the generator 102 console. Theoutput device 147 includes one or more devices for providing a sensoryfeedback to a user. Such devices may comprise, for example, visualfeedback devices (e.g., an LCD display screen, LED indicators), audiofeedback devices (e.g., a speaker, a buzzer) or tactile feedback devices(e.g., haptic actuators).

Although certain modules and/or blocks of the generator 102 may bedescribed by way of example, it can be appreciated that a greater orlesser number of modules and/or blocks may be used and still fall withinthe scope of the embodiments. Further, although various embodiments maybe described in terms of modules and/or blocks to facilitatedescription, such modules and/or blocks may be implemented by one ormore hardware components, e.g., processors, Digital Signal Processors(DSPs), Programmable Logic Devices (PLDs), Application SpecificIntegrated Circuits (ASICs), circuits, registers and/or softwarecomponents, e.g., programs, subroutines, logic and/or combinations ofhardware and software components.

In one embodiment, the ultrasonic generator drive module 108 andelectrosurgery/RF drive module 110 may comprise one or more embeddedapplications implemented as firmware, software, hardware, or anycombination thereof. The modules 108, 110 may comprise variousexecutable modules such as software, programs, data, drivers,application program interfaces (APIs), and so forth. The firmware may bestored in nonvolatile memory (NVM), such as in bit-masked read-onlymemory (ROM) or flash memory. In various implementations, storing thefirmware in ROM may preserve flash memory. The NVM may comprise othertypes of memory including, for example, programmable ROM (PROM),erasable programmable ROM (EPROM), electrically erasable programmableROM (EEPROM), or battery backed random-access memory (RAM) such asdynamic RAM (DRAM), Double-Data-Rate DRAM (DDRAM), and/or synchronousDRAM (SDRAM).

In one embodiment, the modules 108, 110 comprise a hardware componentimplemented as a processor for executing program instructions formonitoring various measurable characteristics of the devices 104, 106and generating a corresponding output drive signal or signals foroperating the devices 104, 106. In embodiments in which the generator102 is used in conjunction with the device 104, the drive signal maydrive the ultrasonic transducer 114 in cutting and/or coagulationoperating modes. Electrical characteristics of the device 104 and/ortissue may be measured and used to control operational aspects of thegenerator 102 and/or provided as feedback to the user. In embodiments inwhich the generator 102 is used in conjunction with the device 106, thedrive signal may supply electrical energy (e.g., RF energy) to the endeffector 132 in cutting, coagulation and/or desiccation modes.Electrical characteristics of the device 106 and/or tissue may bemeasured and used to control operational aspects of the generator 102and/or provided as feedback to the user. In various embodiments, aspreviously discussed, the hardware components may be implemented as DSP,PLD, ASIC, circuits, and/or registers. In one embodiment, the processormay be configured to store and execute computer software programinstructions to generate the step function output signals for drivingvarious components of the devices 104, 106, such as the ultrasonictransducer 114 and the end effectors 126, 132.

FIG. 9 illustrates an equivalent circuit 150 of an ultrasonictransducer, such as the ultrasonic transducer 114, according to oneembodiment. The circuit 150 comprises a first “motional” branch having aserially connected inductance L_(s), resistance R_(s) and capacitanceC_(s) that define the electromechanical properties of the resonator, anda second capacitive branch having a static capacitance C₀. Drive currentI_(g) may be received from a generator at a drive voltage V_(g), withmotional current I_(m) flowing through the first branch and currentI_(g)-I_(m) flowing through the capacitive branch. Control of theelectromechanical properties of the ultrasonic transducer may beachieved by suitably controlling I_(g) and V_(g). As explained above,known generator architectures may include a tuning inductor L_(t) (shownin phantom in FIG. 9) for tuning out in a parallel resonance circuit thestatic capacitance C₀ at a resonant frequency so that substantially allof generator's current output I_(g) flows through the motional branch.In this way, control of the motional branch current I_(m) is achieved bycontrolling the generator current output I_(g). The tuning inductorL_(t) is specific to the static capacitance C₀ of an ultrasonictransducer, however, and a different ultrasonic transducer having adifferent static capacitance requires a different tuning inductor L_(t).Moreover, because the tuning inductor L_(t) is matched to the nominalvalue of the static capacitance C₀ at a single resonant frequency,accurate control of the motional branch current I_(m) is assured only atthat frequency, and as frequency shifts down with transducertemperature, accurate control of the motional branch current iscompromised.

Various embodiments of the generator 102 may not rely on a tuninginductor L_(t) to monitor the motional branch current I_(m). Instead,the generator 102 may use the measured value of the static capacitanceC₀ in between applications of power for a specific ultrasonic surgicaldevice 104 (along with drive signal voltage and current feedback data)to determine values of the motional branch current I_(m) on a dynamicand ongoing basis (e.g., in real-time). Such embodiments of thegenerator 102 are therefore able to provide virtual tuning to simulate asystem that is tuned or resonant with any value of static capacitance C₀at any frequency, and not just at a single resonant frequency dictatedby a nominal value of the static capacitance C₀.

FIG. 10 is a simplified block diagram of one embodiment of the generator102 for proving inductorless tuning as described above, among otherbenefits. FIGS. 11A-11C illustrate an architecture of the generator 102of FIG. 10 according to one embodiment. With reference to FIG. 10, thegenerator 102 may comprise a patient isolated stage 152 in communicationwith a non-isolated stage 154 via a power transformer 156. A secondarywinding 158 of the power transformer 156 is contained in the isolatedstage 152 and may comprise a tapped configuration (e.g., a center-tappedor non-center tapped configuration) to define drive signal outputs 160a, 160 b, 160 c for outputting drive signals to different surgicaldevices, such as, for example, an ultrasonic surgical device 104 and anelectrosurgical device 106. In particular, drive signal outputs 160 a,160 c may output a drive signal (e.g., a 420V RMS drive signal) to anultrasonic surgical device 104, and drive signal outputs 160 b, 160 cmay output a drive signal (e.g., a 100V RMS drive signal) to anelectrosurgical device 106, with output 160 b corresponding to thecenter tap of the power transformer 156. The non-isolated stage 154 maycomprise a power amplifier 162 having an output connected to a primarywinding 164 of the power transformer 156. In certain embodiments thepower amplifier 162 may comprise a push-pull amplifier, for example. Thenon-isolated stage 154 may further comprise a programmable logic device166 for supplying a digital output to a digital-to-analog converter(DAC) 168, which in turn supplies a corresponding analog signal to aninput of the power amplifier 162. In certain embodiments theprogrammable logic device 166 may comprise a field-programmable gatearray (FPGA), for example. The programmable logic device 166, by virtueof controlling the power amplifier's 162 input via the DAC 168, maytherefore control any of a number of parameters (e.g., frequency,waveform shape, waveform amplitude) of drive signals appearing at thedrive signal outputs 160 a, 160 b, 160 c. In certain embodiments and asdiscussed below, the programmable logic device 166, in conjunction witha processor (e.g., processor 174 discussed below), may implement anumber of digital signal processing (DSP)-based and/or other controlalgorithms to control parameters of the drive signals output by thegenerator 102.

Power may be supplied to a power rail of the power amplifier 162 by aswitch-mode regulator 170. In certain embodiments the switch-moderegulator 170 may comprise an adjustable buck regulator, for example.The non-isolated stage 154 may further comprise a processor 174, whichin one embodiment may comprise a DSP processor such as an Analog DevicesADSP-21469 SHARC DSP, available from Analog Devices, Norwood, Mass., forexample. In certain embodiments the processor 174 may control operationof the switch-mode power converter 170 responsive to voltage feedbackdata received from the power amplifier 162 by the processor 174 via ananalog-to-digital converter (ADC) 176. In one embodiment, for example,the processor 174 may receive as input, via the ADC 176, the waveformenvelope of a signal (e.g., an RF signal) being amplified by the poweramplifier 162. The processor 174 may then control the switch-moderegulator 170 (e.g., via a pulse-width modulated (PWM) output) such thatthe rail voltage supplied to the power amplifier 162 tracks the waveformenvelope of the amplified signal. By dynamically modulating the railvoltage of the power amplifier 162 based on the waveform envelope, theefficiency of the power amplifier 162 may be significantly improvedrelative to a fixed rail voltage amplifier schemes.

In certain embodiments and as discussed in further detail in connectionwith FIG. 13, the programmable logic device 166, in conjunction with theprocessor 174, may implement a direct digital synthesizer (DDS) controlscheme to control the waveform shape, frequency and/or amplitude ofdrive signals output by the generator 102. In one embodiment, forexample, the programmable logic device 166 may implement a DDS controlalgorithm 268 by recalling waveform samples stored in adynamically-updated look-up table (LUT), such as a RAM LUT which may beembedded in an FPGA. This control algorithm is particularly useful forultrasonic applications in which an ultrasonic transducer, such as theultrasonic transducer 114, may be driven by a clean sinusoidal currentat its resonant frequency. Because other frequencies may exciteparasitic resonances, minimizing or reducing the total distortion of themotional branch current may correspondingly minimize or reduceundesirable resonance effects. Because the waveform shape of a drivesignal output by the generator 102 is impacted by various sources ofdistortion present in the output drive circuit (e.g., the powertransformer 156, the power amplifier 162), voltage and current feedbackdata based on the drive signal may be input into an algorithm, such asan error control algorithm implemented by the processor 174, whichcompensates for distortion by suitably pre-distorting or modifying thewaveform samples stored in the LUT on a dynamic, ongoing basis (e.g., inreal-time). In one embodiment, the amount or degree of pre-distortionapplied to the LUT samples may be based on the error between a computedmotional branch current and a desired current waveform shape, with theerror being determined on a sample-by sample basis. In this way, thepre-distorted LUT samples, when processed through the drive circuit, mayresult in a motional branch drive signal having the desired waveformshape (e.g., sinusoidal) for optimally driving the ultrasonictransducer. In such embodiments, the LUT waveform samples will thereforenot represent the desired waveform shape of the drive signal, but ratherthe waveform shape that is required to ultimately produce the desiredwaveform shape of the motional branch drive signal when distortioneffects are taken into account.

The non-isolated stage 154 may further comprise an ADC 178 and an ADC180 coupled to the output of the power transformer 156 via respectiveisolation transformers 182, 184 for respectively sampling the voltageand current of drive signals output by the generator 102. In certainembodiments, the ADCs 178, 180 may be configured to sample at highspeeds (e.g., 80 Msps) to enable oversampling of the drive signals. Inone embodiment, for example, the sampling speed of the ADCs 178, 180 mayenable approximately 200× (depending on drive frequency) oversampling ofthe drive signals. In certain embodiments, the sampling operations ofthe ADCs 178, 180 may be performed by a single ADC receiving inputvoltage and current signals via a two-way multiplexer. The use ofhigh-speed sampling in embodiments of the generator 102 may enable,among other things, calculation of the complex current flowing throughthe motional branch (which may be used in certain embodiments toimplement DDS-based waveform shape control described above), accuratedigital filtering of the sampled signals, and calculation of real powerconsumption with a high degree of precision. Voltage and currentfeedback data output by the ADCs 178, 180 may be received and processed(e.g., FIFO buffering, multiplexing) by the programmable logic device166 and stored in data memory for subsequent retrieval by, for example,the processor 174. As noted above, voltage and current feedback data maybe used as input to an algorithm for pre-distorting or modifying LUTwaveform samples on a dynamic and ongoing basis. In certain embodiments,this may require each stored voltage and current feedback data pair tobe indexed based on, or otherwise associated with, a corresponding LUTsample that was output by the programmable logic device 166 when thevoltage and current feedback data pair was acquired. Synchronization ofthe LUT samples and the voltage and current feedback data in this mannercontributes to the correct timing and stability of the pre-distortionalgorithm.

In certain embodiments, the voltage and current feedback data may beused to control the frequency and/or amplitude (e.g., current amplitude)of the drive signals. In one embodiment, for example, voltage andcurrent feedback data may be used to determine impedance phase. Thefrequency of the drive signal may then be controlled to minimize orreduce the difference between the determined impedance phase and animpedance phase setpoint (e.g., 0°), thereby minimizing or reducing theeffects of harmonic distortion and correspondingly enhancing impedancephase measurement accuracy. The determination of phase impedance and afrequency control signal may be implemented in the processor 174, forexample, with the frequency control signal being supplied as input to aDDS control algorithm implemented by the programmable logic device 166.

In another embodiment, for example, the current feedback data may bemonitored in order to maintain the current amplitude of the drive signalat a current amplitude setpoint. The current amplitude setpoint may bespecified directly or determined indirectly based on specified voltageamplitude and power setpoints. In certain embodiments, control of thecurrent amplitude may be implemented by control algorithm, such as, forexample, a proportional-integral-derivative (PID) control algorithm, inthe processor 174. Variables controlled by the control algorithm tosuitably control the current amplitude of the drive signal may include,for example, the scaling of the LUT waveform samples stored in theprogrammable logic device 166 and/or the full-scale output voltage ofthe DAC 168 (which supplies the input to the power amplifier 162) via aDAC 186.

The non-isolated stage 154 may further comprise a processor 190 forproviding, among other things user interface (UI) functionality. In oneembodiment, the processor 190 may comprise an Atmel AT91 SAM9263processor having an ARM 926EJ-S core, available from Atmel Corporation,San Jose, Calif., for example. Examples of UI functionality supported bythe processor 190 may include audible and visual user feedback,communication with peripheral devices (e.g., via a Universal Serial Bus(USB) interface), communication with the footswitch 120, communicationwith an input device 112 (e.g., a touch screen display) andcommunication with an output device 147 (e.g., a speaker). The processor190 may communicate with the processor 174 and the programmable logicdevice (e.g., via serial peripheral interface (SPI) buses). Although theprocessor 190 may primarily support UI functionality, it may alsocoordinate with the processor 174 to implement hazard mitigation incertain embodiments. For example, the processor 190 may be programmed tomonitor various aspects of user input and/or other inputs (e.g., touchscreen inputs, footswitch 120 inputs, temperature sensor inputs) and maydisable the drive output of the generator 102 when an erroneouscondition is detected.

In certain embodiments, both the processor 174 and the processor 190 maydetermine and monitor the operating state of the generator 102. For theprocessor 174, the operating state of the generator 102 may dictate, forexample, which control and/or diagnostic processes are implemented bythe processor 174. For the processor 190, the operating state of thegenerator 102 may dictate, for example, which elements of a userinterface (e.g., display screens, sounds) are presented to a user. Theprocessors 174, 190 may independently maintain the current operatingstate of the generator 102 and recognize and evaluate possibletransitions out of the current operating state. The processor 174 mayfunction as the master in this relationship and determine whentransitions between operating states are to occur. The processor 190 maybe aware of valid transitions between operating states and may confirmif a particular transition is appropriate. For example, when theprocessor 174 instructs the processor 190 to transition to a specificstate, the processor 190 may verify that requested transition is valid.In the event that a requested transition between states is determined tobe invalid by the processor 190, the processor 190 may cause thegenerator 102 to enter a failure mode.

The non-isolated stage 154 may further comprise a controller 196 formonitoring input devices 145 (e.g., a capacitive touch sensor used forturning the generator 102 on and off, a capacitive touch screen). Incertain embodiments, the controller 196 may comprise at least oneprocessor and/or other controller device in communication with theprocessor 190. In one embodiment, for example, the controller 196 maycomprise a processor (e.g., a Mega168 8-bit controller available fromAtmel) configured to monitor user input provided via one or morecapacitive touch sensors. In one embodiment, the controller 196 maycomprise a touch screen controller (e.g., a QT5480 touch screencontroller available from Atmel) to control and manage the acquisitionof touch data from a capacitive touch screen.

In certain embodiments, when the generator 102 is in a “power off”state, the controller 196 may continue to receive operating power (e.g.,via a line from a power supply of the generator 102, such as the powersupply 211 discussed below). In this way, the controller 196 maycontinue to monitor an input device 145 (e.g., a capacitive touch sensorlocated on a front panel of the generator 102) for turning the generator102 on and off. When the generator 102 is in the power off state, thecontroller 196 may wake the power supply (e.g., enable operation of oneor more DC/DC voltage converters 213 of the power supply 211) ifactivation of the “on/off” input device 145 by a user is detected. Thecontroller 196 may therefore initiate a sequence for transitioning thegenerator 102 to a “power on” state. Conversely, the controller 196 mayinitiate a sequence for transitioning the generator 102 to the power offstate if activation of the “on/off” input device 145 is detected whenthe generator 102 is in the power on state. In certain embodiments, forexample, the controller 196 may report activation of the “on/off” inputdevice 145 to the processor 190, which in turn implements the necessaryprocess sequence for transitioning the generator 102 to the power offstate. In such embodiments, the controller 196 may have no independentability for causing the removal of power from the generator 102 afterits power on state has been established.

In certain embodiments, the controller 196 may cause the generator 102to provide audible or other sensory feedback for alerting the user thata power on or power off sequence has been initiated. Such an alert maybe provided at the beginning of a power on or power off sequence andprior to the commencement of other processes associated with thesequence.

In certain embodiments, the isolated stage 152 may comprise aninstrument interface circuit 198 to, for example, provide acommunication interface between a control circuit of a surgical device(e.g., a control circuit comprising handpiece switches) and componentsof the non-isolated stage 154, such as, for example, the programmablelogic device 166, the processor 174 and/or the processor 190. Theinstrument interface circuit 198 may exchange information withcomponents of the non-isolated stage 154 via a communication link thatmaintains a suitable degree of electrical isolation between the stages152, 154, such as, for example, an infrared (IR)-based communicationlink. Power may be supplied to the instrument interface circuit 198using, for example, a low-dropout voltage regulator powered by anisolation transformer driven from the non-isolated stage 154.

In one embodiment, the instrument interface circuit 198 may comprise aprogrammable logic device 200 (e.g., an FPGA) in communication with asignal conditioning circuit 202. The signal conditioning circuit 202 maybe configured to receive a periodic signal from the programmable logicdevice 200 (e.g., a 2 kHz square wave) to generate a bipolarinterrogation signal having an identical frequency. The interrogationsignal may be generated, for example, using a bipolar current source fedby a differential amplifier. The interrogation signal may becommunicated to a surgical device control circuit (e.g., by using aconductive pair in a cable that connects the generator 102 to thesurgical device) and monitored to determine a state or configuration ofthe control circuit. As discussed below in connection with FIGS. 16-32,for example, the control circuit may comprise a number of switches,resistors and/or diodes to modify one or more characteristics (e.g.,amplitude, rectification) of the interrogation signal such that a stateor configuration of the control circuit is uniquely discernable based onthe one or more characteristics. In one embodiment, for example, thesignal conditioning circuit 202 may comprise an ADC for generatingsamples of a voltage signal appearing across inputs of the controlcircuit resulting from passage of interrogation signal therethrough. Theprogrammable logic device 200 (or a component of the non-isolated stage154) may then determine the state or configuration of the controlcircuit based on the ADC samples.

In one embodiment, the instrument interface circuit 198 may comprise afirst data circuit interface 204 to enable information exchange betweenthe programmable logic device 200 (or other element of the instrumentinterface circuit 198) and a first data circuit disposed in or otherwiseassociated with a surgical device. In certain embodiments and withreference to FIGS. 33E-33G, for example, a first data circuit 206 may bedisposed in a cable integrally attached to a surgical device handpiece,or in an adaptor for interfacing a specific surgical device type ormodel with the generator 102. In certain embodiments, the first datacircuit may comprise a non-volatile storage device, such as anelectrically erasable programmable read-only memory (EEPROM) device. Incertain embodiments and referring again to FIG. 10, the first datacircuit interface 204 may be implemented separately from theprogrammable logic device 200 and comprise suitable circuitry (e.g.,discrete logic devices, a processor) to enable communication between theprogrammable logic device 200 and the first data circuit. In otherembodiments, the first data circuit interface 204 may be integral withthe programmable logic device 200.

In certain embodiments, the first data circuit 206 may store informationpertaining to the particular surgical device with which it isassociated. Such information may include, for example, a model number, aserial number, a number of operations in which the surgical device hasbeen used, and/or any other type of information. This information may beread by the instrument interface circuit 198 (e.g., by the programmablelogic device 200), transferred to a component of the non-isolated stage154 (e.g., to programmable logic device 166, processor 174 and/orprocessor 190) for presentation to a user via an output device 147and/or for controlling a function or operation of the generator 102.Additionally, any type of information may be communicated to first datacircuit 206 for storage therein via the first data circuit interface 204(e.g., using the programmable logic device 200). Such information maycomprise, for example, an updated number of operations in which thesurgical device has been used and/or dates and/or times of its usage.

As discussed previously, a surgical instrument may be detachable from ahandpiece (e.g., instrument 124 may be detachable from handpiece 116) topromote instrument interchangeability and/or disposability. In suchcases, known generators may be limited in their ability to recognizeparticular instrument configurations being used and to optimize controland diagnostic processes accordingly. The addition of readable datacircuits to surgical device instruments to address this issue isproblematic from a compatibility standpoint, however. For example,designing a surgical device to remain backwardly compatible withgenerators that lack the requisite data reading functionality may beimpractical due to, for example, differing signal schemes, designcomplexity and cost. Embodiments of instruments discussed below inconnection with FIGS. 16-32 address these concerns by using datacircuits that may be implemented in existing surgical instrumentseconomically and with minimal design changes to preserve compatibilityof the surgical devices with current generator platforms.

Additionally, embodiments of the generator 102 may enable communicationwith instrument-based data circuits, such as those described below inconnection with FIGS. 16-32 and FIGS. 33A-33C. For example, thegenerator 102 may be configured to communicate with a second datacircuit (e.g., data circuit 284 of FIG. 16) contained in an instrument(e.g., instrument 124 or 134) of a surgical device. The instrumentinterface circuit 198 may comprise a second data circuit interface 210to enable this communication. In one embodiment, the second data circuitinterface 210 may comprise a tri-state digital interface, although otherinterfaces may also be used. In certain embodiments, the second datacircuit may generally be any circuit for transmitting and/or receivingdata. In one embodiment, for example, the second data circuit may storeinformation pertaining to the particular surgical instrument with whichit is associated. Such information may include, for example, a modelnumber, a serial number, a number of operations in which the surgicalinstrument has been used, and/or any other type of information.Additionally or alternatively, any type of information may becommunicated to second data circuit for storage therein via the seconddata circuit interface 210 (e.g., using the programmable logic device200). Such information may comprise, for example, an updated number ofoperations in which the instrument has been used and/or dates and/ortimes of its usage. In certain embodiments, the second data circuit maytransmit data acquired by one or more sensors (e.g., an instrument-basedtemperature sensor). In certain embodiments, the second data circuit mayreceive data from the generator 102 and provide an indication to a user(e.g., an LED indication or other visible indication) based on thereceived data.

In certain embodiments, the second data circuit and the second datacircuit interface 210 may be configured such that communication betweenthe programmable logic device 200 and the second data circuit can beeffected without the need to provide additional conductors for thispurpose (e.g., dedicated conductors of a cable connecting a handpiece tothe generator 102). In one embodiment, for example, information may becommunicated to and from the second data circuit using a 1-wire buscommunication scheme implemented on existing cabling, such as one of theconductors used transmit interrogation signals from the signalconditioning circuit 202 to a control circuit in a handpiece. In thisway, design changes or modifications to the surgical device that mightotherwise be necessary are minimized or reduced. Moreover, as discussedin further detail below in connection with FIGS. 16-32 and FIGS.33A-33C, because different types of communications can be implementedover a common physical channel (either with or without frequency-bandseparation), the presence of a second data circuit may be “invisible” togenerators that do not have the requisite data reading functionality,thus enabling backward compatibility of the surgical device instrument.

In certain embodiments, the isolated stage 152 may comprise at least oneblocking capacitor 296-1 connected to the drive signal output 160 b toprevent passage of DC current to a patient. A single blocking capacitormay be required to comply with medical regulations or standards, forexample. While failure in single-capacitor designs is relativelyuncommon, such failure may nonetheless have negative consequences. Inone embodiment, a second blocking capacitor 296-2 may be provided inseries with the blocking capacitor 296-1, with current leakage from apoint between the blocking capacitors 296-1, 296-2 being monitored by,for example, an ADC 298 for sampling a voltage induced by leakagecurrent. The samples may be received by the programmable logic device200, for example. Based on changes in the leakage current (as indicatedby the voltage samples in the embodiment of FIG. 10), the generator 102may determine when at least one of the blocking capacitors 296-1, 296-2has failed. Accordingly, the embodiment of FIG. 10 may provide a benefitover single-capacitor designs having a single point of failure.

In certain embodiments, the non-isolated stage 154 may comprise a powersupply 211 for outputting DC power at a suitable voltage and current.The power supply may comprise, for example, a 400 W power supply foroutputting a 48 VDC system voltage. The power supply 211 may furthercomprise one or more DC/DC voltage converters 213 for receiving theoutput of the power supply to generate DC outputs at the voltages andcurrents required by the various components of the generator 102. Asdiscussed above in connection with the controller 196, one or more ofthe DC/DC voltage converters 213 may receive an input from thecontroller 196 when activation of the “on/off” input device 145 by auser is detected by the controller 196 to enable operation of, or wake,the DC/DC voltage converters 213.

FIG. 13 illustrates certain functional and structural aspects of oneembodiment of the generator 102. Feedback indicating current and voltageoutput from the secondary winding 158 of the power transformer 156 isreceived by the ADCs 178, 180, respectively. As shown, the ADCs 178, 180may be implemented as a 2-channel ADC and may sample the feedbacksignals at a high speed (e.g., 80 Msps) to enable oversampling (e.g.,approximately 200× oversampling) of the drive signals. The current andvoltage feedback signals may be suitably conditioned in the analogdomain (e.g., amplified, filtered) prior to processing by the ADCs 178,180. Current and voltage feedback samples from the ADCs 178, 180 may beindividually buffered and subsequently multiplexed or interleaved into asingle data stream within block 212 of the programmable logic device166. In the embodiment of FIG. 13, the programmable logic device 166comprises an FPGA.

The multiplexed current and voltage feedback samples may be received bya parallel data acquisition port (PDAP) implemented within block 214 ofthe processor 174. The PDAP may comprise a packing unit for implementingany of a number of methodologies for correlating the multiplexedfeedback samples with a memory address. In one embodiment, for example,feedback samples corresponding to a particular LUT sample output by theprogrammable logic device 166 may be stored at one or more memoryaddresses that are correlated or indexed with the LUT address of the LUTsample. In another embodiment, feedback samples corresponding to aparticular LUT sample output by the programmable logic device 166 may bestored, along with the LUT address of the LUT sample, at a common memorylocation. In any event, the feedback samples may be stored such that theaddress of an LUT sample from which a particular set of feedback samplesoriginated may be subsequently ascertained. As discussed above,synchronization of the LUT sample addresses and the feedback samples inthis way contributes to the correct timing and stability of thepre-distortion algorithm. A direct memory access (DMA) controllerimplemented at block 216 of the processor 174 may store the feedbacksamples (and any LUT sample address data, where applicable) at adesignated memory location 218 of the processor 174 (e.g., internalRAM).

Block 220 of the processor 174 may implement a pre-distortion algorithmfor pre-distorting or modifying the LUT samples stored in theprogrammable logic device 166 on a dynamic, ongoing basis. As discussedabove, pre-distortion of the LUT samples may compensate for varioussources of distortion present in the output drive circuit of thegenerator 102. The pre-distorted LUT samples, when processed through thedrive circuit, will therefore result in a drive signal having thedesired waveform shape (e.g., sinusoidal) for optimally driving theultrasonic transducer.

At block 222 of the pre-distortion algorithm, the current through themotional branch of the ultrasonic transducer is determined. The motionalbranch current may be determined using Kirchoff's Current Law based on,for example, the current and voltage feedback samples stored at memorylocation 218 (which, when suitably scaled, may be representative ofI_(g) and V_(g) in the model of FIG. 9 discussed above), a value of theultrasonic transducer static capacitance C₀ (measured or known a prion)and a known value of the drive frequency. A motional branch currentsample for each set of stored current and voltage feedback samplesassociated with a LUT sample may be determined.

At block 224 of the pre-distortion algorithm, each motional branchcurrent sample determined at block 222 is compared to a sample of adesired current waveform shape to determine a difference, or sampleamplitude error, between the compared samples. For this determination,the sample of the desired current waveform shape may be supplied, forexample, from a waveform shape LUT 226 containing amplitude samples forone cycle of a desired current waveform shape. The particular sample ofthe desired current waveform shape from the LUT 226 used for thecomparison may be dictated by the LUT sample address associated with themotional branch current sample used in the comparison. Accordingly, theinput of the motional branch current to block 224 may be synchronizedwith the input of its associated LUT sample address to block 224. TheLUT samples stored in the programmable logic device 166 and the LUTsamples stored in the waveform shape LUT 226 may therefore be equal innumber. In certain embodiments, the desired current waveform shaperepresented by the LUT samples stored in the waveform shape LUT 226 maybe a fundamental sine wave. Other waveform shapes may be desirable. Forexample, it is contemplated that a fundamental sine wave for drivingmain longitudinal motion of an ultrasonic transducer superimposed withone or more other drive signals at other frequencies, such as a thirdorder harmonic for driving at least two mechanical resonances forbeneficial vibrations of transverse or other modes, could be used.

Each value of the sample amplitude error determined at block 224 may betransmitted to the LUT of the programmable logic device 166 (shown atblock 228 in FIG. 13) along with an indication of its associated LUTaddress. Based on the value of the sample amplitude error and itsassociated address (and, optionally, values of sample amplitude errorfor the same LUT address previously received), the LUT 228 (or othercontrol block of the programmable logic device 166) may pre-distort ormodify the value of the LUT sample stored at the LUT address such thatthe sample amplitude error is reduced or minimized. It will beappreciated that such pre-distortion or modification of each LUT samplein an iterative manner across the entire range of LUT addresses willcause the waveform shape of the generator's output current to match orconform to the desired current waveform shape represented by the samplesof the waveform shape LUT 226.

Current and voltage amplitude measurements, power measurements andimpedance measurements may be determined at block 230 of the processor174 based on the current and voltage feedback samples stored at memorylocation 218. Prior to the determination of these quantities, thefeedback samples may be suitably scaled and, in certain embodiments,processed through a suitable filter 232 to remove noise resulting from,for example, the data acquisition process and induced harmoniccomponents. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal. In certain embodiments, the filter 232 may be afinite impulse response (FIR) filter applied in the frequency domain.Such embodiments may use the fast Fourier transform (FFT) of the outputdrive signal current and voltage signals. In certain embodiments, theresulting frequency spectrum may be used to provide additional generatorfunctionality. In one embodiment, for example, the ratio of the secondand/or third order harmonic component relative to the fundamentalfrequency component may be used as a diagnostic indicator.

At block 234, a root mean square (RMS) calculation may be applied to asample size of the current feedback samples representing an integralnumber of cycles of the drive signal to generate a measurement I_(rms)representing the drive signal output current.

At block 236, a root mean square (RMS) calculation may be applied to asample size of the voltage feedback samples representing an integralnumber of cycles of the drive signal to determine a measurement V_(rms)representing the drive signal output voltage.

At block 238, the current and voltage feedback samples may be multipliedpoint by point, and a mean calculation is applied to samplesrepresenting an integral number of cycles of the drive signal todetermine a measurement P_(r) of the generator's real output power.

At block 240, measurement P_(a) of the generator's apparent output powermay be determined as the product V_(rms)·I_(rms).

At block 242, measurement Z_(m) of the load impedance magnitude may bedetermined as the quotient V_(rms)/I_(rms).

In certain embodiments, the quantities I_(rms), V_(rms), P_(r), P_(a)and Z_(m) determined at blocks 234, 236, 238, 240 and 242 may be used bythe generator 102 to implement any of number of control and/ordiagnostic processes. In certain embodiments, any of these quantitiesmay be communicated to a user via, for example, an output device 147integral with the generator 102 or an output device 147 connected to thegenerator 102 through a suitable communication interface (e.g., a USBinterface). Various diagnostic processes may include, withoutlimitation, handpiece integrity, instrument integrity, instrumentattachment integrity, instrument overload, approaching instrumentoverload, frequency lock failure, over-voltage, over-current,over-power, voltage sense failure, current sense failure, audioindication failure, visual indication failure, short circuit, powerdelivery failure, blocking capacitor failure, for example.

Block 244 of the processor 174 may implement a phase control algorithmfor determining and controlling the impedance phase of an electricalload (e.g., the ultrasonic transducer) driven by the generator 102. Asdiscussed above, by controlling the frequency of the drive signal tominimize or reduce the difference between the determined impedance phaseand an impedance phase setpoint (e.g., 0°), the effects of harmonicdistortion may be minimized or reduced, and the accuracy of the phasemeasurement increased.

The phase control algorithm receives as input the current and voltagefeedback samples stored in the memory location 218. Prior to their usein the phase control algorithm, the feedback samples may be suitablyscaled and, in certain embodiments, processed through a suitable filter246 (which may be identical to filter 232) to remove noise resultingfrom the data acquisition process and induced harmonic components, forexample. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal.

At block 248 of the phase control algorithm, the current through themotional branch of the ultrasonic transducer is determined. Thisdetermination may be identical to that described above in connectionwith block 222 of the pre-distortion algorithm. The output of block 248may thus be, for each set of stored current and voltage feedback samplesassociated with a LUT sample, a motional branch current sample.

At block 250 of the phase control algorithm, impedance phase isdetermined based on the synchronized input of motional branch currentsamples determined at block 248 and corresponding voltage feedbacksamples. In certain embodiments, the impedance phase is determined asthe average of the impedance phase measured at the rising edge of thewaveforms and the impedance phase measured at the falling edge of thewaveforms.

At block 252 of the of the phase control algorithm, the value of theimpedance phase determined at block 222 is compared to phase setpoint254 to determine a difference, or phase error, between the comparedvalues.

At block 256 of the phase control algorithm, based on a value of phaseerror determined at block 252 and the impedance magnitude determined atblock 242, a frequency output for controlling the frequency of the drivesignal is determined. The value of the frequency output may becontinuously adjusted by the block 256 and transferred to a DDS controlblock 268 (discussed below) in order to maintain the impedance phasedetermined at block 250 at the phase setpoint (e.g., zero phase error).In certain embodiments, the impedance phase may be regulated to a 0°phase setpoint. In this way, any harmonic distortion will be centeredabout the crest of the voltage waveform, enhancing the accuracy of phaseimpedance determination.

Block 258 of the processor 174 may implement an algorithm for modulatingthe current amplitude of the drive signal in order to control the drivesignal current, voltage and power in accordance with user specifiedsetpoints, or in accordance with requirements specified by otherprocesses or algorithms implemented by the generator 102. Control ofthese quantities may be realized, for example, by scaling the LUTsamples in the LUT 228 and/or by adjusting the full-scale output voltageof the DAC 168 (which supplies the input to the power amplifier 162) viaa DAC 186. Block 260 (which may be implemented as a PID controller incertain embodiments) may receive as input current feedback samples(which may be suitably scaled and filtered) from the memory location218. The current feedback samples may be compared to a “current demand”I_(d) value dictated by the controlled variable (e.g., current, voltageor power) to determine if the drive signal is supplying the necessarycurrent. In embodiments in which drive signal current is the controlvariable, the current demand I_(d) may be specified directly by acurrent setpoint 262A (I_(sp)). For example, an RMS value of the currentfeedback data (determined as in block 234) may be compared touser-specified RMS current setpoint I_(sp) to determine the appropriatecontroller action. If, for example, the current feedback data indicatesan RMS value less than the current setpoint I_(sp), LUT scaling and/orthe full-scale output voltage of the DAC 168 may be adjusted by theblock 260 such that the drive signal current is increased. Conversely,block 260 may adjust LUT scaling and/or the full-scale output voltage ofthe DAC 168 to decrease the drive signal current when the currentfeedback data indicates an RMS value greater than the current setpointI_(sp).

In embodiments in which the drive signal voltage is the controlvariable, the current demand I_(d) may be specified indirectly, forexample, based on the current required maintain a desired voltagesetpoint 262B (V_(sp)) given the load impedance magnitude Z_(m) measuredat block 242 (e.g. I_(d)=V_(sp)/Z_(m)). Similarly, in embodiments inwhich drive signal power is the control variable, the current demandI_(d) may be specified indirectly, for example, based on the currentrequired to maintain a desired power setpoint 262C (P_(sp)) given thevoltage V_(rms) measured at blocks 236 (e.g. I_(d)=P_(sp)/V_(rms)).

Block 268 may implement a DDS control algorithm for controlling thedrive signal by recalling LUT samples stored in the LUT 228. In certainembodiments, the DDS control algorithm be a numerically-controlledoscillator (NCO) algorithm for generating samples of a waveform at afixed clock rate using a point (memory location)-skipping technique. TheNCO algorithm may implement a phase accumulator, or frequency-to-phaseconverter, that functions as an address pointer for recalling LUTsamples from the LUT 228. In one embodiment, the phase accumulator maybe a D step size, modulo N phase accumulator, where D is a positiveinteger representing a frequency control value, and N is the number ofLUT samples in the LUT 228. A frequency control value of D=1, forexample, may cause the phase accumulator to sequentially point to everyaddress of the LUT 228, resulting in a waveform output replicating thewaveform stored in the LUT 228. When D>1, the phase accumulator may skipaddresses in the LUT 228, resulting in a waveform output having a higherfrequency. Accordingly, the frequency of the waveform generated by theDDS control algorithm may therefore be controlled by suitably varyingthe frequency control value. In certain embodiments, the frequencycontrol value may be determined based on the output of the phase controlalgorithm implemented at block 244. The output of block 268 may supplythe input of (DAC) 168, which in turn supplies a corresponding analogsignal to an input of the power amplifier 162.

Block 270 of the processor 174 may implement a switch-mode convertercontrol algorithm for dynamically modulating the rail voltage of thepower amplifier 162 based on the waveform envelope of the signal beingamplified, thereby improving the efficiency of the power amplifier 162.In certain embodiments, characteristics of the waveform envelope may bedetermined by monitoring one or more signals contained in the poweramplifier 162. In one embodiment, for example, characteristics of thewaveform envelope may be determined by monitoring the minima of a drainvoltage (e.g., a MOSFET drain voltage) that is modulated in accordancewith the envelope of the amplified signal. A minima voltage signal maybe generated, for example, by a voltage minima detector coupled to thedrain voltage. The minima voltage signal may be sampled by ADC 176, withthe output minima voltage samples being received at block 272 of theswitch-mode converter control algorithm. Based on the values of theminima voltage samples, block 274 may control a PWM signal output by aPWM generator 276, which, in turn, controls the rail voltage supplied tothe power amplifier 162 by the switch-mode regulator 170. In certainembodiments, as long as the values of the minima voltage samples areless than a minima target 278 input into block 262, the rail voltage maybe modulated in accordance with the waveform envelope as characterizedby the minima voltage samples. When the minima voltage samples indicatelow envelope power levels, for example, block 274 may cause a low railvoltage to be supplied to the power amplifier 162, with the full railvoltage being supplied only when the minima voltage samples indicatemaximum envelope power levels. When the minima voltage samples fallbelow the minima target 278, block 274 may cause the rail voltage to bemaintained at a minimum value suitable for ensuring proper operation ofthe power amplifier 162.

FIGS. 33A-33C illustrate control circuits of surgical devices accordingto various embodiments. As discussed above in connection with FIG. 10, acontrol circuit may modify characteristics of an interrogation signaltransmitted by the generator 102. The characteristics of theinterrogation signal, which may uniquely indicate a state orconfiguration of the control circuit, can be discerned by the generator102 and used to control aspects of its operation. The control circuitsmay be contained in an ultrasonic surgical device (e.g., in handpiece116 of ultrasonic surgical device 104), or in an electrosurgical device(e.g., in handpiece 130 of electrosurgical device 106).

Referring to the embodiment of FIG. 33A, control circuit 300-1 may beconnected to the generator 102 to receive an interrogation signal (e.g.,a bipolar interrogation signal at 2 kHz) from the signal conditioningcircuit 202 (e.g., from generator terminals HS and SR (FIG. 10) via aconductive pair of cable 112 or cable 128). The control circuit 300-1may comprise a first branch that includes series-connected diodes D1 andD2 and a switch SW1 connected in parallel with D2. The control circuit300-1 may also comprise a second branch that includes series-connecteddiodes D3, D4 and D5, a switch SW2 connected in parallel with D4, and aresistor R1 connected in parallel with D5. In certain embodiments and asshown, D5 may be a Zener diode. The control circuit 300-1 mayadditionally comprise a data storage element 302 that, together with oneor more components of the second branch (e.g., D5, R1), define a datacircuit 304. In certain embodiments, the data storage element 302, andpossibly other components of the data circuit 304, may be contained inthe instrument (e.g., instrument 124, instrument 134) of the surgicaldevice, with other components of the control circuit 300-1 (e.g., SW1,SW2, D1, D2, D3, D4) being contained in the handpiece (e.g., handpiece116, handpiece 130). In certain embodiments, the data storage element302 may be a single-wire bus device (e.g., a single-wire protocolEEPROM), or other single-wire protocol or local interconnect network(LIN) protocol device. In one embodiment, for example, the data storageelement 302 may comprise a Maxim DS28EC20 1-Wire® EEPROM, available fromMaxim Integrated Products, Inc., Sunnyvale, Calif. The data storageelement 302 is one example of a circuit element that may be contained inthe data circuit 304. The data circuit 304 may additionally oralternatively comprise one or more other circuit elements or componentscapable of transmitting or receiving data. Such circuit elements orcomponents may be configured to, for example, transmit data acquired byone or more sensors (e.g., an instrument-based temperature sensor)and/or receive data from the generator 102 and provide an indication toa user (e.g., an LED indication or other visible indication) based onthe received data.

During operation, an interrogation signal (e.g., a bipolar interrogationsignal at 2 kHz) from the signal conditioning circuit 202 may be appliedacross both branches of the control circuit 300-1. In this way, thevoltage appearing across the branches may be uniquely determined by thestates of SW1 and SW2. For example, when SW1 is open, the voltage dropacross the control circuit 300-1 for negative values of theinterrogation signal will be sum of the forward voltage drops across D1and D2. When SW1 is closed, the voltage drop for negative values of theinterrogation signal will be determined by the forward voltage drop ofD1 only. Thus, for example, with a forward voltage drop of 0.7 volts foreach of D1 and D2, open and closed states of SW1 may correspond tovoltage drops of 1.4 volts and 0.7 volts, respectively. In the same way,the voltage drop across the control circuit 300-1 for positive values ofthe interrogation signal may be uniquely determined by the state of SW2.For example, when SW2 is open, the voltage drop across the controlcircuit 300-1 will be the sum of the forward voltage drops across D3 andD4 (e.g., 1.4 volts) and the breakdown voltage of D5 (e.g., 3.3 volts).When SW2 is closed, the voltage drop across the control circuit 300-1will be the sum of the forward voltage drop across D3 and the breakdownvoltage of D5. Accordingly, the state or configuration of SW1 and SW2may be discerned by the generator 102 based on the interrogation signalvoltage appearing across the inputs of the control circuit 300-1 (e.g.,as measured by an ADC of the signal conditioning circuit 202).

In certain embodiments, the generator 102 may be configured tocommunicate with the data circuit 304, and, in particular, with the datastorage element 302, via the second data circuit interface 210 (FIG. 10)and the conductive pair of cable 112 or cable 128. The frequency band ofthe communication protocol used to communicate with the data circuit 304may be higher than the frequency band of the interrogation signal. Incertain embodiments, for example, the frequency of the communicationprotocol for the data storage element 302 may be, for example, 200 kHzor a significantly higher frequency, whereas the frequency of theinterrogation signal used to determine the different states of SW1 andSW2 may be, for example, 2 kHz. Diode D5 may limit the voltage suppliedto the data storage element 302 to a suitable operating range (e.g.,3.3-5V).

As explained above in connection with FIG. 10, the data circuit 304,and, in particular, the data storage element 302, may store informationpertaining to the particular surgical instrument with which it isassociated. Such information may be retrieved by the generator 102 andinclude, for example, a model number, a serial number, a number ofoperations in which the surgical instrument has been used, and/or anyother type of information. Additionally, any type of information may becommunicated from the generator 102 to the data circuit 304 for storagein the data storage element 302. Such information may comprise, forexample, an updated number of operations in which the instrument hasbeen used and/or dates and/or times of its usage.

As noted above, the data circuit 304 may additionally or alternativelycomprise components or elements other than the data storage element 302for transmitting or receiving data. Such components or elements may beconfigured to, for example, transmit data acquired by one or moresensors (e.g., an instrument-based temperature sensor) and/or receivedata from the generator 102 and provide an indication to a user (e.g.,an LED indication or other visible indication) based on the receiveddata.

Embodiments of the control circuit may comprise additional switches.With reference to the embodiment of FIG. 33B, for example, controlcircuit 300-2 may comprise a first branch having a first switch SW1 anda second switch SW2 (for a total of three switches), with eachcombination of SW1 and SW2 states corresponding to a unique voltage dropacross the control circuit 300-2 for negative values of theinterrogation signal. For example, the open and closed states of SW1 addor remove, respectively, the forward voltage drops of D2 and D3, and theopen and closed states of SW2 add or remove, respectively, the forwardvoltage drop of D4. In the embodiment of FIG. 33C, the first branch ofcontrol circuit 300-3 comprises three switches (for a total of fourswitches), with the breakdown voltage of Zener diode D2 being used todistinguish changes in the voltage drop resulting from the operation ofSW1 from voltage changes resulting from the operation of SW2 and SW3.

FIGS. 14 and 15 illustrate control circuits of surgical devicesaccording to various embodiments. As discussed above in connection withFIG. 10, a control circuit may modify characteristics of aninterrogation signal transmitted by the generator 102. Thecharacteristics of the interrogation signal, which may uniquely indicatethe state or configuration of the control circuit, can be discerned bythe generator 102 and used to control aspects of its operation. Thecontrol circuit 280 of FIG. 14 may be contained in an ultrasonicsurgical device (e.g., in handpiece 116 of ultrasonic surgical device104), and the control circuit 282 of FIG. 15 may be contained in anelectrosurgical device (e.g., in handpiece 130 of electrosurgical device106).

Referring to FIG. 14, control circuit 280 may be connected to thegenerator 102 to receive an interrogation signal (e.g., a bipolarinterrogation signal at 2 kHz) from the signal conditioning circuit 202(e.g., from generator terminals HS and SR (FIG. 10) via a conductivepair of cable 112). The control circuit 280 may comprise a first switchSW1 in series with a first diode D1 to define a first branch, and asecond switch SW2 in series with a second diode D2 to define a secondbranch. The first and second branches may be connected in parallel suchthat the forward conduction direction of D2 is opposite that of D1. Theinterrogation signal may be applied across both branches. When both SW1and SW2 are open, the control circuit 280 may define an open circuit.When SW1 is closed and SW2 is open, the interrogation signal may undergohalf-wave rectification in a first direction (e.g., positive half ofinterrogation signal blocked). When SW1 is open and SW2 is closed, theinterrogation signal may undergo half-wave rectification in a seconddirection (e.g., negative half of interrogation signal blocked). Whenboth SW1 and SW2 are closed, no rectification may occur. Accordingly,based on the different characteristics of the interrogation signalcorresponding to the different states of SW1 and SW2, the state orconfiguration of the control circuit 280 may be discerned by thegenerator 102 based on a voltage signal appearing across the inputs ofthe control circuit 280 (e.g., as measured by an ADC of the signalconditioning circuit 202).

In certain embodiments and as shown in FIG. 14, the cable 112 maycomprise a data circuit 206. The data circuit 206 may comprise, forexample, a non-volatile storage device, such as an EEPROM device. Thegenerator 102 may exchange information with the data circuit 206 via thefirst data circuit interface 204 as discussed above in connection withFIG. 10. Such information may be specific to a surgical device integralwith, or configured for use with, the cable 112 and may comprise, forexample, a model number, a serial number, a number of operations inwhich the surgical device has been used, and/or any other type ofinformation. Information may also be communicated from the generator 102to the data circuit 206 for storage therein, as discussed above inconnection with FIG. 10. In certain embodiments and with reference toFIGS. 33E-33G, the data circuit 206 may be disposed in an adaptor forinterfacing a specific surgical device type or model with the generator102.

Referring to FIG. 15, control circuit 282 may be connected to thegenerator 102 to receive an interrogation signal (e.g., a bipolarinterrogation signal at 2 kHz) from the signal conditioning circuit 202(e.g., from generator terminals HS and SR (FIG. 10) via a conductivepair of cable 128). The control circuit 282 may compriseseries-connected resistors R2, R3 and R4, with switches SW1 and SW2connected across R2 and R4, respectively. The interrogation signal maybe applied across at least one of the series-connected resistors togenerate a voltage drop across the control circuit 282. For example,when both SW1 and SW2 are open, the voltage drop may be determined byR2, R3 and R4. When SW1 is closed and SW2 is open, the voltage drop maybe determined by R3 and R4. When SW1 is open and SW2 is closed, thevoltage drop may be determined by R2 and R3. When both SW1 and SW2 areclosed, the voltage drop may be determined by R3. Accordingly, based onthe voltage drop across the control circuit 282 (e.g., as measured by anADC of the signal conditioning circuit 202), the state or configurationof the control circuit 282 may be discerned by the generator 102.

FIG. 16 illustrates one embodiment of a control circuit 280-1 of anultrasonic surgical device, such as the ultrasonic surgical device 104.The control circuit 280-1, in addition to comprising components of thecontrol circuit 280 of FIG. 14, may comprise a data circuit 284 having adata storage element 286. In certain embodiments, the data storageelement 286, and possibly other components of the data circuit 284, maybe contained in the instrument (e.g., instrument 124) of the ultrasonicsurgical device, with other components of the control circuit 280-1(e.g., SW1, SW2, D1, D2, D3, D4, C1) being contained in the handpiece(e.g., handpiece 116). In certain embodiments, the data storage element286 may be a single-wire bus device (e.g., a single-wire protocolEEPROM), or other single-wire protocol or local interconnect network(LIN) protocol device. In one embodiment, for example, the data storageelement 286 may comprise a Maxim DS28EC20 1-Wire® EEPROM, available fromMaxim Integrated Products, Inc., Sunnyvale, Calif.

In certain embodiments, the generator 102 may be configured tocommunicate with the data circuit 284, and, in particular, with the datastorage element 286, via the second data circuit interface 210 (FIG. 10)and the conductive pair of the cable 112. In particular, the frequencyband of the communication protocol used to communicate with the datacircuit 284 may be higher than the frequency band of the interrogationsignal. In certain embodiments, for example, the frequency of thecommunication protocol for the data storage element 286 may be, forexample, 200 kHz or a significantly higher frequency, whereas thefrequency of the interrogation signal used to determine the differentstates of SW1 and SW2 may be, for example, 2 kHz. Accordingly, the valueof capacitor C1 of the data circuit 284 may be selected such that thedata storage element 286 is “hidden” from the relatively low frequencyof the interrogation signal while allowing the generator 102 tocommunicate with the data storage element 286 at the higher frequency ofthe communication protocol. A series diode D3 may protect the datastorage element 286 from negative cycles of the interrogation signal,and a parallel Zener diode D4 may limit the voltage supplied to the datastorage element 286 to a suitable operating range (e.g., 3.3-5V). Whenin the forward conduction mode, D4 may also clamp negative cycles of theinterrogation signal to ground.

As explained above in connection with FIG. 10, the data circuit 284,and, in particular, the data storage element 286, may store informationpertaining to the particular surgical instrument with which it isassociated. Such information may be retrieved by the generator 102 andinclude, for example, a model number, a serial number, a number ofoperations in which the surgical instrument has been used, and/or anyother type of information. Additionally, any type of information may becommunicated from the generator 102 to the data circuit 284 for storagein the data storage element 286. Such information may comprise, forexample, an updated number of operations in which the instrument hasbeen used and/or dates and/or times of its usage. Moreover, because thedifferent types of communications between the generator 102 and thesurgical device may be frequency-band separated, the presence of thedata storage element 286 may be “invisible” to generators that do nothave the requisite data reading functionality, thus enabling backwardcompatibility of the surgical device.

In certain embodiments and as shown in FIG. 17, the data circuit 284-1may comprise an inductor L1 to provide isolation of the data storageelement 286 from the states of SW1 and SW2. The addition of L1 mayadditionally enable use of the data circuit 284-1 in electrosurgicaldevices. FIG. 18, for example, illustrates one embodiment of a controlcircuit 282-1 that combines the control circuit 282 of FIG. 15 with thedata circuit 284-1 of FIG. 17.

In certain embodiments, a data circuit may comprise one or more switchesto modify one or more characteristics (e.g., amplitude, rectification)of an interrogation signal received by the data circuit such that astate or configuration of the one or more switches is uniquelydiscernable based on the one or more characteristics. FIG. 19, forexample, illustrates one embodiment of a control circuit 282-2 in whichthe data circuit 284-2 comprises a switch SW3 connected in parallel withD4. An interrogation signal may be communicated from the generator 102(e.g., from the signal conditioning circuit 202 of FIG. 10) at afrequency sufficient for the interrogation signal to be received by thedata circuit 284-2 via C1 but blocked from other portions of the controlcircuit 282-2 by L1. In this way, one or more characteristics of a firstinterrogation signal (e.g., a bipolar interrogation signal at 25 kHz)may be used to discern the state of SW3, and one or more characteristicsof a second interrogation signal at a lower frequency (e.g., a bipolarinterrogation signal at 2 kHz) may be used to discern the states of SW1and SW2. Although the addition of SW3 is illustrated in connection withthe control circuit 282-2 in an electrosurgical device, it will beappreciated that SW3 may be added to a control circuit of an ultrasonicsurgical device, such as, for example, the control circuit 280-2 of FIG.17.

Additionally, it will be appreciated that switches in addition to SW3may be added to a data circuit. As shown in FIGS. 20 and 21, forexample, embodiments of the data circuit 284-3 and 284-4, respectively,may comprise a second switch SW4. In FIG. 20, voltage values of Zenerdiodes D5 and D6 may be selected such that their voltage valuessufficiently differ to allow reliable discrimination of theinterrogation signal in the presence of noise. The sum of the voltagesvalues of D5 and D6 may be equal to or less than the voltage value ofD4. In certain embodiments, depending upon the voltages values of D5 andD6, it may be possible to eliminate D4 from the embodiment of the datacircuit 284-3 illustrated in FIG. 20.

In certain cases, the switches (e.g., SW1-SW4) may impede the ability ofthe generator 102 to communicate with the data storage element 286. Inone embodiment, this issue may be addressed by declaring an error if thestates of the switches are such that they will interfere withcommunication between the generator 102 and the data storage element286. In another embodiment, the generator 102 may only permitcommunication with the data storage element 286 when determined by thegenerator 102 that the states of the switches will not interfere withthe communication. Because the states of the switches may beunpredictable to an extent, the generator 102 may make thisdetermination on a recurring basis. The addition of L1 in certainembodiments may prevent interference caused by switches external to thedata circuit (e.g., SW1 and SW2). For switches contained within the datacircuit (e.g., SW3 and SW4), isolation of the switches by frequency bandseparation may be realized by the addition of a capacitor C2 having acapacitance value significantly smaller than C1 (e.g., C2<<C1).Embodiments of data circuits 284-5, 284-6, 284-7 comprising C2 are shownin FIGS. 22-24, respectively.

In any of the embodiments of FIGS. 16-24, depending on the frequencyresponse characteristics of D4, it may be desirable or necessary to adda fast diode in parallel with D4 and pointing in the same direction.

FIG. 25 illustrates one embodiment of a control circuit 280-5 in whichcommunication between the generator 102 and a data storage element isimplemented using an amplitude-modulated communication protocol (e.g.,amplitude-modulated 1-Wire® protocol, amplitude-modulated LIN protocol).Amplitude modulation of the communication protocol on a high-frequencycarrier (e.g., 8 MHz or higher) substantially increases frequency bandseparation between low frequency interrogation signals (e.g.,interrogation signals at 2 kHz) and the native “baseband” frequency ofthe communication protocol used in the embodiments of FIGS. 16-24. Thecontrol circuit 280-5 may be similar to the control circuit 280-1 ofFIG. 16, with the data circuit 288 comprising an additional capacitor C3and resistor R5, which, in conjunction with D3, demodulate theamplitude-modulated communication protocol for receipt by the datastorage element 286. As in the embodiment of FIG. 16, D3 may protect thedata storage element 286 from negative cycles of the interrogationsignal, and D4 may limit the voltage supplied to the data storageelement 286 to a suitable operating range (e.g., 3.3-5V) and clampnegative cycles of the interrogation signal to ground when in theforward conduction mode. The increased frequency separation may allow C1to be somewhat small relative to the embodiments of FIGS. 16-24.Additionally, the higher frequency of the carrier signal may alsoimprove noise immunity of communications with the data storage elementbecause it is further removed from the frequency range of electricalnoise that may be generated by other surgical devices used in the sameoperating room environment. In certain embodiments, the relatively highfrequency of the carrier in combination with the frequency responsecharacteristics of D4 may make it desirable or necessary to add a fastdiode in parallel with D4 and pointing in the same direction.

With the addition of an inductor L1 to prevent interference with datastorage element 286 communications caused by switches external to thedata circuit 288 (e.g., SW1 and SW2), the data circuit 288 may be usedin control circuits of electrosurgical instruments, as shown in theembodiment of the data circuit 288-1 of FIG. 26.

With the exception of C2 and R3, and the more likely need for D7, theembodiments of FIGS. 25 and 26 are similar to the “baseband” embodimentsof FIGS. 16-24. For example, the manner in which switches may be addedto the data circuits of FIGS. 19-21 is directly applicable to theembodiments of FIGS. 25 and 26 (including the possibility of eliminatingD4 from the modulated-carrier equivalent of the FIG. 20).Modulated-carrier equivalents of the data circuits embodied in FIGS.22-24 may simply require the addition of an appropriately-sized inductorL2 in series with C2 in order to isolate the interrogation frequency forthe additional switches (e.g., SW3, SW4) to an intermediate frequencyband between the carrier frequency and the lower interrogation frequencyfor switches external to the data circuit. An embodiment of one suchdata circuit 282-7 is shown in FIG. 27.

In the embodiment of FIG. 27, any interference with the generator'sability to communicate with the data storage element 286 caused bystates of SW1 and SW2 may be addressed as described above in connectionwith the embodiments of FIGS. 19-24. For example, the generator 102 maydeclare an error if switch states will prevent communication, or thegenerator 102 may only permit communication when determined by thegenerator 102 that the switch states will not cause interference.

In certain embodiments, the data circuit may not comprise a data storageelement 286 (e.g., an EEPROM device) to store information. FIGS. 28-32illustrate embodiments of control circuits that utilize resistive and/orinductive elements to modify one or more characteristics of aninterrogation signal (e.g., amplitude, phase) such that a state orconfiguration of the control circuit may be uniquely discerned based onthe one or more characteristics.

In FIG. 28, for example, the data circuit 290 may comprise anidentification resistor R1, with the value of C1 selected such that R1is “hidden” from a first low frequency interrogation signal (e.g., aninterrogation signal at 2 kHz) for determining the states of SW1 andSW2. By measuring the voltage and/or current (e.g., amplitude, phase) atthe inputs of the control circuit 280-6 resulting from a secondinterrogation signal within a substantially higher frequency band, thegenerator 102 may measure the value of R1 through C1 in order todetermine which of a plurality of identification resistors is containedin the instrument. Such information may be used by the generator 102 toidentify the instrument, or a particular characteristic of theinstrument, so that control and diagnostic processes may be optimized.Any interference with the generator's ability to measure R1 caused bystates of SW1 and SW2 may be addressed by declaring an error if switchstates will prevent measurement, or by maintaining the voltage of thesecond higher-frequency interrogation signal below the turn-on voltagesof D1 and D2. Such interference may also be addressed by adding aninductor in series with the switch circuitry (L1 in FIG. 29) to blockthe second higher-frequency interrogation signal while passing thefirst, lower-frequency interrogation signal. The addition of an inductorin this manner may also enable the use of the data circuit 290 incontrol circuits of electrosurgical instruments, as shown in theembodiment of the data circuit 290-2 of FIG. 30.

In certain embodiments, multiple capacitors C1 for allowinginterrogation at multiple frequencies could be used to differentiatebetween a larger number of distinct R1 values for a givensignal-to-noise ratio, or for a given set of component tolerances. Inone such embodiment, inductors may be placed in series with all but thelowest value of C1 to create specific pass bands for differentinterrogation frequencies, as shown in the embodiment of the datacircuit 290-3 in FIG. 31.

In embodiments of control circuits based on the control circuit 280 ofFIG. 14, identification resistors may be measured without the need forfrequency band separation. FIG. 32 illustrates one such embodiment, withR1 selected to have a relatively high value.

FIGS. 33D-331 illustrate embodiments of multi-conductor cables andadaptors that may be used to establish electrical communication betweenthe generator 102 and a handpiece of a surgical device. In particular,the cables may transmit the generator drive signal to surgical deviceand enable control-based communications between the generator 102 and acontrol circuit of the surgical device. In certain embodiments, thecables may be integrally formed with the surgical device or configuredfor removable engagement by a suitable connector of the surgical device.Cables 112-1, 112-2 and 112-3 (FIGS. 33E-33G, respectively) may beconfigured for use with an ultrasonic surgical device (e.g., ultrasonicsurgical device 104), and cable 128-1 (FIG. 33D) may be configured foruse with an electrosurgical device (e.g., electrosurgical device 106).One or more of the cables may be configured to connect directly with thegenerator 102, such as cable 112-1, for example. In such embodiments,the cable may comprise a data circuit (e.g., data circuit 206) forstoring information pertaining to the particular surgical device withwhich it is associated (e.g., a model number, a serial number, a numberof operations in which the surgical device has been used, and/or anyother type of information). In certain embodiments, one or more of thecables may connect to the generator 102 via an adaptor. For example,cables 112-2 and 112-3 may connect to the generator 102 via a firstadaptor 292 (FIG. 33I), and cable 128-1 may connect to the generator 102via a second adaptor 294 (FIG. 33H). In such embodiments, a data circuit(e.g., data circuit 206) may be disposed in the cable (e.g., cables112-2 and 112-3) or in the adaptor (e.g., second adaptor 294).

In various embodiments, the generator 102 may be electrically isolatedfrom the surgical devices 104, 106 in order to prevent undesired andpotentially harmful currents in the patient. For example, if thegenerator 102 and the surgical devices 104, 106 were not electricallyisolated, voltage provided to the devices 104, 106 via the drive signalcould potentially change the electrical potential of patent tissue beingacted upon by the device or devices 104, 106 and, thereby, result inundesired currents in the patient. It will be appreciated that suchconcerns may be more acute when the using a ultrasonic surgical device104 that is not intended to pass any current though tissue. Accordingly,the remainder of the description of active cancellation of leakagecurrent is described in terms of a ultrasonic surgical device 104. Itwill be appreciated, however, that the systems and methods describedherein may be applicable to electrosurgical devices 106 as well.

According to various embodiments, an isolation transformer, such as theisolation transformer 156, may be used to provide electrical isolationbetween the generator 102 and the surgical device 104. For example, thetransformer 156 may provide isolation between the non-isolated stage 154and the isolated stage 152 described above. The isolated stage 154 maybe in communication with the surgical device 104. The drive signal maybe provided by the generator 102 (e.g., the generator module 108) to theprimary winding 164 of the isolation transformer 156 and provided to thesurgical device 104 from the secondary winding 158 of the isolationtransformer. Considering the non-idealities of real transformers,however, this arrangement may not provide complete electrical isolation.For example, a real transformer may have stray capacitance between theprimary and secondary windings. The stray capacitance may preventcomplete electrical isolation and allow electrical potential present onthe primary winding to affect the potential of the secondary winding.This may result in leakage currents within the patient.

Contemporary industry standards, such as the InternationalElectrotechnical Commission (IEC) 60601-1 standard limit allowablepatient leakage current to 10 μA or less. Leakage current may bepassively reduced by providing a leakage capacitor between the secondarywinding of the isolation transformer and ground (e.g., earth ground).The leakage capacitor may operate to smooth changes in patient-sidepotential coupled from the non-isolated side via the stray capacitanceof the isolation transformer and thereby reduce leakage current. As thevoltage, current, power and/or frequency of the drive signal provided bythe generator 102 increase, however, the leakage current may alsoincrease. In various embodiments, induced leakage current may increasebeyond the capability of a passive leakage capacitor to keep it below 10μA and/or other leakage current standards.

Accordingly, various embodiments are directed to systems and methods foractively cancelling leakage current. FIG. 34 illustrates one embodimentof a circuit 800 for active cancellation of leakage current. The circuit800 may be implemented as a part of or in conjunction with the generator102. The circuit may comprise an isolation transformer 802 having aprimary winding 804 and a secondary winding 806. The drive signal 816may be provided across the primary winding 804, generating an isolateddrive signal across the secondary winding 806. In addition to theisolated drive signal, stray capacitance 808 of the isolationtransformer 802 may couple some component of the potential of the drivesignal relative to ground 818 to the secondary winding 806 on thepatient side.

A leakage capacitor 810 and active cancellation circuit 812 may beprovided, as shown, connected between the secondary winding 806 andground 818. The active cancellation circuit 812 may generate an inversedrive signal 814 that may be about 180° out of phase with the drivesignal 816. The active cancellation circuit 812 may be electricallycoupled to the leakage capacitor 810 to drive the leakage capacitor to apotential that, relative to ground 818, is about 180° out of phase withthe drive signal 816. Accordingly, electrical charge on the patient-sidesecondary winding 806 may reach ground 818 via the leakage capacitor 810instead of through the patient, reducing leakage current. According tovarious embodiments, the leakage capacitor 810 may be designed to meetadequate, industry, government and/or design standards for robustness.For example, the leakage capacitor 810 may be a Y-type capacitorcomplying with the IEC 60384-14 standard and/or may comprise multiplephysical capacitors in series.

FIG. 35 illustrates one embodiment of a circuit 820 that may beimplemented by the generator 102 to provide active cancellation ofleakage current. The circuit 820 may comprise a generator circuit 824and a patient-side circuit 822. The generator circuit 824 may generateand/or modulate the drive signal, as described herein. For example, insome embodiments, the generator circuit 824 may operate similar to thenon-isolated stage 154 described above. Also, for example, thepatient-side circuit 822 may operate similar to the isolated state 152described above.

Electrical isolation between the generator circuit 824 and thepatient-side circuit 822 may be provided by an isolation transformer826. The primary winding 828 of the isolation transformer 826 may becoupled to the generator circuit 824. For example, the generator circuit824 may generate the drive signal across the primary winding 828. Thedrive signal may be generated across the primary winding 828 accordingto any suitable method. For example, according to various embodiments,the primary winding 828 may comprise a center tap 829 that may be heldto a DC voltage (e.g., 48 volts). The generator circuit 824 may compriseoutput stages 825, 827 that are, respectively, coupled to the other endsof the primary winding 828. Output stages 825, 827 may cause currentscorresponding to the drive signal to flow in the primary winding 828.For example, positive portions of the drive signal may be realized whenthe output stage 827 pulls its output voltage lower than the center tapvoltage, causing the output stage 827 to sink current from across theprimary winding 828. A corresponding current may be induced in thesecondary winding 830. Likewise, negative portions of the drive signalmay be implemented when the output state 827 pulls its output voltagelower than the center tap voltage, causing the output stage 825 to sinkan opposite current across the primary winding 828. This may induce acorresponding, opposite current in the secondary winding 830. Thepatient-side circuit 822 may perform various signal conditioning and/orother processing to the isolated drive signal, which may be provided toa device 104 via output lines 821, 823.

An active cancellation transformer 832 may have a primary winding 834and a secondary winding 836. The primary winding 834 may be electricallycoupled to the primary winding 828 of the isolation transformer 826 suchthat the drive signal is provided across the winding 834. For example,the primary winding 834 may comprise two windings 843, 845. A first end835 of the first winding 845 and a first end 839 of the second winding843 may be electrically coupled to the center tap 829 of the winding828. A second end 841 of the first winding 845 may be electricallycoupled to the output stage 827, while a second end 837 of the secondwinding 843 may be electrically coupled to the output state 825. Thesecondary winding 836 of the cancellation transformer 832 may be coupledto ground 818 and to a first electrode of a cancellation capacitor 840.The other electrode of the cancellation capacitor 840 may be coupled tothe output line 823. An optional load resistor 838 may also beelectrically coupled in parallel across the secondary winding 836.

According to various embodiments, the secondary winding 836 of theactive cancellation transformer may be wound and/or wired to the othercomponents 840, 838, 818, such that its polarity is opposite thepolarity of the primary winding 834. For example, an inverse drivesignal may be induced across the secondary winding 836. Relative toground 818, the inverse drive signal may be 180° out of phase with thedrive signal provided across the primary winding 834 of the activecancellation transform 832. In conjunction with the load resistor 838,the secondary winding 836 may provide the inverse drive signal at thecancellation capacitor 840. Accordingly, charge causing leakagepotential appearing at the patient-side circuit 822 due to the drivesignal may be drawn to the cancellation capacitor 840. In this way, thecapacitor 840, secondary winding 836 and load resistor 838 may sinkpotential leakage current to ground 818, minimizing patient leakagecurrent.

According to various embodiments, the parameters of the components 832,838, 840 may be selected to maximize leakage current cancellation and,in various embodiments, to lessen electromagnetic emissions. Forexample, the active cancellation transformer 832 may be made frommaterials and according to a construction that allows it to match thefrequency, temperature, humidity and other characteristics of theisolation transformer 826. Other parameters of the active transformer832 (e.g., number of turns, turn ratios, etc.) may be selected toachieve a balance between minimizing output-induced current,electromagnetic (EM) emissions and leakage current due to appliedexternal voltage. For example, the circuit 820 may be configured to meetthe IEC 60601 or other suitable industry or government standards. Thevalue of the load resistor 838 may be similarly chosen. In addition, theparameters of the cancellation capacitor 840 (e.g., capacitance, etc.)may be selected to match, as well as possible, the characteristics ofthe stray capacitances responsible for the inducing leakage current.

FIG. 36 illustrates an alternate embodiment of a circuit 842 that may beimplemented by the generator 102 to provide active cancellation ofleakage current. The circuit 842 may be similar to the circuit 820,however, the secondary winding 836 of the active cancellationtransformation 832 may be electrically coupled to the output line 823.The cancellation capacitor 823 may be connected in series between thesecondary winding 836 and ground 818. The circuit 842 may operate in amanner similar to that of the circuit 820. According to variousembodiments, (e.g., when the active cancellation transformer 832 is astep-up transformer), the total working voltage, for example, as definedin IEC 60601-1, may be minimized.

FIG. 37 illustrates an alternate embodiment of a circuit 844 that may beimplemented by the generator 102 to provide active cancellation ofleakage current. The circuit 844 may omit the active cancellationtransformer 832 and replace it with a second secondary winding 846 ofthe isolation transformer 826. The second secondary winding 846 may beconnected to the output line 823. The cancellation capacitor 840 may beconnected in series between the second secondary winding 846 and ground.The second secondary winding may be wound and or wired with a polarityopposite that of the primary winding 828 and the secondary winding 830.Accordingly, when the drive signal is present across the primary winding828, the inverse drive signal, as described above, may be present acrossthe secondary winding 846. Accordingly, the circuit 844 may cancelleakage current in a manner similar to that described above with respectto the circuits 820 and 842. Omitting the active cancellationtransformer 832, as shown in circuit 844, may reduce part count, costand complexity.

FIG. 38 illustrates yet another embodiment of a circuit 848 that may beimplemented by the generator 102 to provide active cancellation ofleakage current. The circuit 848 may be configured to cancel extraneouscurrents in the patient side circuit 822 due to capacitive coupling, asdescribed above, as well as other external effects such as, for example,frequency-specific effects (e.g., 60 Hz or other frequency noise frompower supplies), path effects, load effects, etc. Instead of beingelectrically coupled to ground 818, the cancellation capacitor 840, asshown in the circuit 848, may be coupled to an correction controlcircuit 851. The circuit 851 may comprise a digital signal processor(DSP) 850 or other processor. The DSP 850 may receive inputs 858 (e.g.,via an analog-to-digital converter). The inputs 858 may be valuestending to indicate external effects that may cause additional leakagecurrent. Examples of such inputs may be, for example, power supplyparameters, load data such as impedance, impedance or other valuesdescribing the path from the circuit 848 to the device 104, etc. Basedon the inputs 858, the DSP 85 may derive a cancellation potential that,when provided to the cancellation capacitor 840, may cancel patient-sidecurrents due to the external effects. The cancellation potential may beprovided, digitally, to digital-to-analog converter 852, which mayprovide an analog version of the cancellation potential to thecancellation capacitor 840. Accordingly, the voltage drop across thecancellation capacitor 840 may be a function of the inverse drivesignal, present across the second secondary winding 846 and thecancellation potential found by the circuit 851.

The circuit 848 is shown with the active cancellation transformer 832omitted and the capacitor 840 and second secondary winding 846 in theconfiguration of the circuit 844. It will be appreciated, however, thatthe correction control circuit 851 may be utilized in any of theconfigurations described herein (e.g., 820, 842, 844, etc.). Forexample, the correction control circuit 851 may be substituted forground 818 in any of the circuits 820, 842, 844.

FIG. 39 illustrated an embodiment of a circuit 860 that may beimplemented by the generator 102 to provide cancellation of leakagecurrent. According to the circuit 860, the cancellation capacitor 840may be connected between the primary winding 828 of the isolationtransformer 826 and the output line 823 (e.g., the common output line).In this way, the inverse of the drive signal may appear across thecancellation capacitor 840, bringing about a similar leakage currentcancellation effect to those described above.

FIG. 40 illustrates another embodiment of a circuit 862 that may beimplemented by the generator 102 to provide cancellation of leakagecurrent. The circuit 862 may be similar to the circuit 860 with theexception that the cancellation capacitor may be connected between theoutput line 823 (e.g., the common output line) and two additionalcapacitors 864, 866. Capacitor 864 may be connected between thecancellation capacitor 840 and the primary winding 828 of the isolationtransformer 826. Capacitor 866 maybe connected between the cancellationcapacitor 840 and ground 818. The combination of the capacitors 864, 866may provide a radio frequency (RF) path to ground that may enhance theRF performance of the generator 102 (e.g., by decreasing electromagneticemissions).

A surgical generator, such as the generator 102 schematicallyillustrated in FIG. 10, for example, may be electrically coupled to avariety of surgical instruments. The surgical instruments may include,for example, both RF-based instruments and ultrasonic-based devices.FIG. 41 illustrates a receptacle and connector interface 900 inaccordance with one non-limiting embodiment. In one embodiment, theinterface 900 comprises a receptacle assembly 902 and a connectorassembly 920. The connector assembly 920 may be electrically coupled tothe distal end of a cable 921 that is ultimately connected to a handheldsurgical instrument, for example. FIG. 59 illustrates a surgicalgenerator 1050 in accordance with one non-limiting embodiment. Thesurgical generator 1050 may comprise a surgical generator body 1052 thatgenerally includes the outer shell of the generator. The surgical body1052 may define an aperture 1054 for receiving a receptacle assembly,such as the receptacle assembly 1058 illustrated in FIG. 59. Referringnow to FIGS. 41 and 59, the receptacle assembly 902 may comprise a seal906 to generally prevent fluid ingress into the surgical generator 1050by was of the aperture 1054. In one embodiment, the seal 906 is an epoxyseal.

FIG. 42 is an exploded side view of the receptacle assembly 902 inaccordance with one non-limiting embodiment. The receptacle assembly 902may include a variety of components, such as a magnet 212, for example.The receptacle assembly 902 may also comprise a plurality of sockets 908that may be arranged in a generally circular formation, or any othersuitable formation. FIG. 48 is an enlarged view of a socket 908 inaccordance with one non-limiting embodiment. In one embodiment, thesocket 908 is bifurcated and the receptacle assembly 902 includes ninebifurcated sockets 908, while greater or few sockets may be utilized inother embodiments. Each of the sockets 908 may define an inner cavity910 for receiving electrically conductive pins, as discussed in moredetail below. In some embodiments, various sockets 908 will be mountedwithin the receptacle assembly 902 at different elevations such thatcertain sockets are contacted prior to other sockets when a connectorassembly is inserted into the receptacle assembly.

FIG. 43 is an exploded side view of the connector assembly 920 inaccordance with one non-limiting embodiment. The connector assembly 920may comprise, for example, a connector body 922 that includes aninsertion portion 924 that is sized to be received by the receptacleassembly 902, as described in more detail below. The connector assembly920 may comprise a variety of other components, such as a ferrous pin926, a circuit board 928, and a plurality of electrically conductivepins 930. As shown in FIG. 54, the ferrous pin 926 may be cylindrical.In other embodiments, the ferrous pin 926 may be other shapes, such asrectangular, for example. The ferrous pin 926 may be steel, iron, or anyother magnetically compatible material that is attracted to magneticfields or that may be magnetizable. The ferrous pin 926 may also have ashoulder 927, or other type of laterally extending feature. Referringnow to FIG. 55, the electrical conductive pins 930 may be affixed to andextend from the circuit board 928. The circuit board 928 may alsoinclude device identification circuitry, such as the circuitsillustrated in FIGS. 33E-33G, for example. Thus, in various embodiments,the circuit board 928 may carry EEPROM, resistors, or any otherelectrical components. In some embodiments, portions of the circuitboard 928 may be potted, or otherwise encapsulated, to improve thesterility of the surgical device and assist in water resistance.

Referring again to FIG. 43, the connector assembly 920 may also includea strain relief member 932. As shown in FIG. 56, the strain reliefmember 932 generally accepts cable loading to prevent that loading frombeing applied to the circuit board 928 and/or the sockets 908. In someembodiments, the strain relief member 932 may include an alignment notch934 to aid in assembly. Referring again to FIG. 43, the connectorassembly 920 may also include a boot 936 that is coupled to theconnector body 922. FIG. 57 illustrates the boot 936 in accordance withone non-limiting embodiment. The boot 936 may generally serve as bendrelief for an associated cable and assist in sealing the connectorassembly 920. In some embodiments, the boot 936 may snap onto theconnector body 922. For autoclave applications, the boot 936 may be anovermolded component. In other embodiments, other attachment techniquesmay be used, such as adhesives or spin welding, for example.

FIG. 44 is a perspective view of the receptacle assembly 902 shown inFIG. 41. FIG. 45 is an exploded perspective view of the receptacleassembly 902. FIG. 46 is a front elevation view of the receptacleassembly 902. FIG. 47 is a side elevation view of the receptacleassembly 902. Referring to FIGS. 44-47, the receptacle assembly 902 maycomprise a flange 950. The flange 950 may have an inner wall 952 and anouter wall 954. Spanning the inner wall 952 and the outer wall 954 is aflange surface 956. The inner wall 952 may include at least one curvedportion and at least one linear portion. The inner wall 952 of theflange 950 defines a cavity 960 having a unique geometry. In oneembodiment, the cavity 960 is defined by about 270 degrees of a circleand two linear segments that are tangential to the circle and intersectto form an angle Θ. In one embodiment, angle Θ is about 90 degrees. Inone embodiment, a central protruding portion 962 having an outerperiphery 964 is positioned in the cavity 960. The central protrudingportion 962 may have a central surface 966 that defines a recess 968.The magnet 912 (FIG. 42) may be positioned proximate the recess 968. Asillustrated, the sockets 908 may be positioned through apertures 972defined by the central surface 966 of the central protruding portion962. In embodiments utilizing a circular arrangement of sockets 908, themagnet 912 may be positioned internal to the circle defined by thesockets. The receptacle body 904 may also define a rear recess 976 (FIG.47). The rear recess 976 may be sized to receive the seal 906. Theflange face 966 may be slanted at an angle β (FIG. 47). As illustratedin FIG. 61, a face of the body 1052 of the surgical generator 1050 alsomay be slanted at the angle β as well.

FIG. 49 is a perspective view of the connector assembly 920 and FIG. 50is an exploded perspective view of the connector assembly 920. FIG. 51is a side elevation view of the connector body 922 with FIGS. 52 and 53illustrating perspective views of the distal and proximal ends,respectively, of the connector body 922. Referring now to FIGS. 49-53,connector body 922 may have a flange 980. The flange 980 may comprise atleast one curved portion and at least one linear portion.

The adapter assemblies 1002 and 1004 may comprise substantially thesimilar components that are contained by the connector body 922 (FIG.50). For example, the adapter assemblies 1002 and 1004 may each house acircuit board with device identification circuitry. The adapterassemblies 1002 and 1004 may also each house one of a ferrous pin and amagnet to aid in the connection with the surgical generator. An outerwall 982 of the flange 980 may generally be shaped similarly to theinner wall 952 of the receptacle assembly 902 (FIG. 46). An inner wall984 of the flange 980 may be shaped similarly to the outer periphery 964of the central protruding portion 962. The connector body 922 may alsohave a wall 988 that includes a plurality of apertures 990. Theapertures 990 may be sized to receive the electrically conductive pins930 and the ferrous pin 926. In one embodiment, the shoulder 927 of theferrous pin 926 is sized so that it can not pass through the aperture990. In some embodiments, the ferrous pin 926 may be able to translatewith respect to the wall 988. When assembled, the shoulder 927 of theferrous pin 926 may be positioned intermediate the wall 988 and thecircuit board 928. The ferrous pin 926 may be positioned such that itencounters the magnetic field of the magnet 912 when the connectorassembly 920 is inserted into the receptacle assembly 902. In someembodiments, a proper connection will be denoted by an audible clickwhen the ferrous pin 926 translates to the wall 988 and strikes themagnet 912. As is to be appreciated, various components may bepositioned intermediate the ferrous pin 926 and the magnet 912, such asa washer, for example, to reduce incidental wear to the interfacingcomponents. Additionally, in some embodiments the magnet 912 may becoupled to the connector assembly 920 and the ferrous pin 926 may becoupled to the receptacle assembly 902.

FIG. 58 illustrates two adaptor assemblies 1002 and 1004 in accordancewith various non-limiting embodiments. The adaptor assemblies 1002 and1004 allow of connector assemblies having various geometries to beelectrically coupled to a receptacle assembly of a surgical generator.Adaptor assembly 1002 is configured to accommodate a surgical instrumenthaving connector assembly 1006 and adaptor assembly 1004 is configuredto accommodate a surgical instrument having a connector assembly 1008.In one embodiment, the connector assembly 1006 is associated with anRF-based surgical device via a cable 1060 and the connector assembly1008 is associated with an ultrasonic-based device via a cable 1062. Asis to be appreciated, other embodiments of adaptor assemblies mayaccommodate surgical instruments have connector assemblies differentthan those illustrated in FIG. 58. FIG. 59 illustrates the adaptorassembly 1002 after being inserting into the receptacle assembly 1058 ofa surgical generator 1050 in accordance with one non-limitingembodiment. FIG. 60 illustrates the connector assembly 1006 after beinginserted into the adaptor assembly 1002 and therefore electricallycoupled to the surgical generator 1050. Similarly, FIG. 61 illustratesthe adaptor assembly 1004 after being inserted into the receptacleassembly 1058 of a surgical generator 1050 in accordance with onenon-limiting embodiment. FIG. 62 illustrates the connector assembly 1008after being inserted into the adaptor assembly 1004. Accordingly, whileconnector assemblies 1006 and 1008 each having different geometries,both may be used with the surgical generator 1050.

Referring to FIGS. 58-62, in one embodiment, the adaptor assembly 1002has a distal portion 1010 that comprises a flange 1012. The flange 1012is configured to be inserted into the receptacle assembly 1058 of thesurgical instrument 1050 and may be similar to the flange 980illustrated in FIG. 52, for example. Any number of electricallyconductive pins, or other connection components, may be positioned inthe distal portion to engage the receptacle assembly 1058. In oneembodiment, the adaptor assembly 1002 also has a proximal portion 1014that defines a cavity 1016. The cavity 1016 may be configured to accepta particular connector assembly, such as connector assembly 1006. As isto be appreciated, the proximal portion 1014 may be configuredappropriately based on the type of connector assembly with which it willbe used. In one embodiment, the adaptor assembly 1006 has a distalportion 1020 that comprises a flange 1022. The flange 1022 is configuredto be inserted into the receptacle assembly 1058 of the surgicalinstrument 1050 and may be similar to the flange 980 illustrated in FIG.52, for example. The adaptor assembly 1004 also has a proximal portion1024 that defines a cavity 1026. In the illustrated embodiment, thecentral portion 1028 is positioned in the cavity 1026 and is configuredto accept the connector assembly 1008.

FIG. 63 illustrates a perspective view of a back panel 1100 of agenerator 1102 in accordance with one non-limiting embodiment. Thegenerator 1102 may be similar to generator 102 illustrated in FIG. 10,for example. The back panel 1100 may comprise various input and/oroutput ports 1104. The back panel 1110 may also comprise an electronicpaper display device 1106. The electronic paper display device 1106 maybe based on electrophoresis in which an electromagnetic field is appliedto a conductive material such that the conductive material has mobility.Micro particles having conductivity are distributed between thin-typeflexible substrates, and positions of the micro particles (or tonerparticles) are changed due to the change of the polarities of anelectromagnetic field, whereby data is displayed. The technical approachto realize the electronic paper may be accomplished using any suitabletechnique, such as liquid crystals, organic electro luminescence (EL),reflective film reflection-type display, electrophoresis, twist balls,or mechanical reflection-type display, for example. Generally,electrophoresis is a phenomenon in which, when particles are suspendedin a medium (i.e., a dispersion medium), the particles are electricallycharged, and, when an electric field is applied to the chargedparticles, the particles move to an electrode having opposite chargethrough the dispersion medium. Further discussion regarding electronicpaper display devices may be found in U.S. Pat. No. 7,751,115 entitledELECTRONIC PAPER DISPLAY DEVICE, MANUFACTURING METHOD AND DRIVING METHODTHEREOF, the entirety of which is incorporated by reference.

FIG. 64 illustrates the back panel 1110 illustrated in FIG. 63. FIGS. 65and 66 provide enlarged views of the back panel 1110. Referring to FIGS.64-66, the electronic paper display device 1106 may display a variety ofinformation, such a serial number, a part number, patent numbers,warning labels, port identifiers, instructions, vendor information,service information, manufacturer information, operational information,or any other type of information. In one embodiment, the informationdisplayed on the electronic paper display device 1106 may be changed orupdated through connecting a computing device to a communication port(e.g., a USB port) of the generator 1102.

As shown in FIG. 66, in some embodiments, the back panel 1100 maycomprise an interactive portion 1108. In one embodiment, the interactiveportion 1108 allows a user to input information to the generator 1102using input devices, such as buttons 1110. The interactive portion 1108may also display information that is simultaneously displayed on a frontpanel (not shown) of the generator 1102.

In a surgical procedure utilizing an ultrasonic surgical device, such asthe ultrasonic surgical device 104, the end effector 126 transmitsultrasonic energy to tissue brought into contact with the end effector126 to realize cutting and sealing action. The application of ultrasonicenergy in this manner may cause localized heating of the tissue.Monitoring and controlling such heating may be desirable to minimizeunintended tissue damage and/or to optimize the effectiveness of thecutting and sealing action. Direct measurement of ultrasonic heatingrequires temperature sensing devices in or near the end effector 126.Although sensor-based measurements of ultrasonic heating is technicallyfeasible, design complexity and other considerations may make directmeasurement impractical. Various embodiments of the generator 102 mayaddress this problem by generating an estimate of temperature or heatingresulting from an application of ultrasonic energy.

In particular, one embodiment of the generator 102 may implement anartificial neural network to estimate ultrasonic heating based on anumber of input variables 1218. Artificial neural networks aremathematical models that learn complex, nonlinear relationships betweeninputs and outputs based on exposure to known input and output patterns,a process commonly referred to as “training.” An artificial neuralnetwork may comprise a network of simple processing units, or nodes,connected together to perform data processing tasks. The structure of anartificial neural network may be somewhat analogous to the structure ofbiological neural networks in the brain. When an artificial neuralnetwork is presented with an input data pattern, it produces an outputpattern. An artificial neural network may be trained for a specificprocessing task by presentation of large amounts of training data. Inthis way, the artificial neural network may modify its structure bychanging the “strength” of communication between nodes to improve itsperformance on the training data.

FIG. 67 illustrates one embodiment of an artificial neural network 1200for generating an estimated temperature T_(est) resulting from anapplication of ultrasonic energy using an ultrasonic surgical device,such as the ultrasonic surgical device 104. In certain embodiments, theneural network may be implemented in the processor 174 and/or theprogrammable logic device 166 of the generator 102. The neural network1200 may comprise an input layer 1202, one or more nodes 1204 defining ahidden layer 1206, and one or more nodes 1208 defining an output layer1210. For the sake of clarity, only one hidden layer 1206 is shown. Incertain embodiments, the neural network 1200 may comprise one or moreadditional hidden layers in a cascaded arrangement, with each additionalhidden layer having a number of nodes 1204 that may be equal to ordifferent from the number of nodes 1204 in the hidden layer 1206.

Each node 1204, 1208 in the layers 1202, 1210 may include one or moreweight values w 1212, a bias value b 1214, and a transform function ƒ1216. In FIG. 67, the use of different subscripts for these values andfunctions is intended to illustrate that each of these values andfunctions may be different from the other values and functions. Theinput layer 1202 comprises one or more input variables p 1218, with eachnode 1204 of the hidden layer 1206 receiving as input at least one ofthe input variables p 1218. As shown in FIG. 67, for example, each node1204 may receive all of the input variables p 1218. In otherembodiments, less than all of the input variables p 1218 may be receivedby a node 1204. Each input variable p 1218 received by a particular node1204 is weighted by a corresponding weight value w 1212, then added toany other similarly weighted input variables p 1218, and to the biasvalue b 1214. The transform function ƒ 1216 of the node 1204 is thenapplied to the resulting sum to generate the node's output. In FIG. 67,for example, the output of node 1204-1 may be given as f₁(n₁, wheren₁=(w_(1,1)·p₁+w_(1,2)·p₂+ . . . +w_(1,j)·p_(j))+b₁.

A particular node 1208 of the output layer 1210 may receive an outputfrom one or more of the nodes 1204 of the hidden layer 1206 (e.g., eachnode 1208 receives outputs f₁(·), f₂(·), . . . , f_(i)(·) fromrespective nodes 1204-1, 1204-2, . . . , 1204-i in FIG. 67), with eachreceived output being weighted by a corresponding weight value w 1212and subsequently added to any other similarly weighted received outputs,and to a bias value b 1214. The transform function ƒ 1216 of the node1208 is then applied to the resulting sum to generate the node's output,which corresponds to an output of the neural network 1200 (e.g., theestimated temperature T_(est) in the embodiment of FIG. 67). Althoughthe embodiment of the neural network 1200 in FIG. 67 comprises only onenode 1208 in the output layer 1210, in other embodiments the neuralnetwork 1200 may comprise more than one output, in which case the outputlayer 1210 may comprise multiple nodes 1208.

In certain embodiments, the transform function ƒ 1216 of a node 1204,1208 may be a nonlinear transfer function. In one embodiment, forexample, one or more of the transform functions ƒ 1216 may be a sigmoidfunction. In other embodiments, the transform functions ƒ 1216 mayinclude a tangent sigmoid, a hyperbolic tangent sigmoid, a logarithmicsigmoid, a linear transfer function, a saturated linear transferfunction, a radial basis transfer function, or some other type oftransfer function. The transform function ƒ 1216 of a particular node1204, 1208 may be the same as, or different from, a transform function ƒ1216 in another node 1204, 1208.

In certain embodiments, the input variables p 1218 received by the nodes1204 of the hidden layer 1206 may represent, for example, signals and/orother quantities or conditions known or believed to have an effect onthe temperature or heating resulting from an application of ultrasonicenergy. Such variables may comprise, for example, one or more of: drivevoltage output by the generator 102, drive current output by thegenerator 102, drive frequency of the generator output 102, drive poweroutput by the generator 102, drive energy output by the generator 102,impedance of the ultrasonic transducer 114, and time duration over whichultrasonic energy is applied. Additionally, one or more of the inputvariables p 1218 may be unrelated to outputs of the generator 102 andmay comprise, for example, characteristics of the end effector 126(e.g., blade tip size, geometry, and/or material) and a particular typeof tissue targeted by the ultrasonic energy.

The neural network 1200 may be trained (e.g., by changing or varying theweight values w 1212, the bias values b 1214, and the transformfunctions ƒ 1216) such that its output (e.g., estimated temperatureT_(est) in the embodiment of FIG. 67) suitably approximates a measureddependency of the output for known values of the input variables p 1218.Training may be performed, for example, by supplying known sets of inputvariables p 1218, comparing output of the neural network 1200 tomeasured outputs corresponding to the known sets of input variables p1218, and modifying the weight values w 1212, the bias values b 1214,and/or the transform functions ƒ 1216 until the error between theoutputs of the neural network 1200 and the corresponding measuredoutputs is below a predetermined error level. For example, the neuralnetwork 1200 may be trained until the mean square error is below apredetermined error threshold. In certain embodiments, aspects of thetraining process may be implemented by the neural network 1200 (e.g., bypropagating errors back through the network 1200 to adaptively adjustthe weight values w 1212 and/or the bias values b 1214).

FIG. 68 illustrates a comparison between estimated temperature valuesT_(est) and measured temperature values T_(m) for an implementation ofone embodiment of the neural network 1200. The neural network 1200 usedto generate T_(est) in FIG. 68 comprised six input variables p 1218:drive voltage, drive current, drive frequency, drive power, impedance ofthe ultrasonic transducer, and time duration over which ultrasonicenergy was applied. The hidden layer 1206 comprised 25 nodes, and theoutput layer 1210 comprised a single node 1208. Training data wasgenerated based on 13 applications of ultrasonic energy to carotidvessels. Actual temperature (T_(m)) was determined based on IRmeasurements over a 250-sample range for varying values of the inputvariables p 1218, with estimated temperatures T_(est) being generated bythe neural network 1200 based on corresponding values of the inputvariables p 1218. The data shown in FIG. 68 was generated on a run thatwas excluded from the training data. The estimated temperatures T_(est)demonstrate a reasonably accurate approximation of the measuredtemperatures T_(m) in the region of 110-190° F. It is believed thatinconsistencies in estimated temperatures T_(est) appearing in certainregions, such as the region following 110° F., may be minimized orreduced by implementing additional neural networks specific to thoseregions. Additionally, inconsistencies in the data that may skew thetrained output of the neural network 1200 may be identified andprogrammed in as special cases to further improve performance.

In certain embodiments, when the estimated temperature exceeds auser-defined temperature threshold T_(th), the generator 102 may beconfigured to control the application of ultrasonic energy such that theestimated temperature T_(est) is maintained at or below the temperaturethreshold T_(th). For example, in embodiments in which the drive currentis an input variable p 1218 to the neural network 1200, the drivecurrent may be treated as a control variable and modulated to minimizeor reduce the difference between T_(est) and T_(th). Such embodimentsmay be implemented using a feedback control algorithm (e.g., a PIDcontrol algorithm), with T_(th) being input to the control algorithm asa setpoint, T_(est) being input to the algorithm as process variablefeedback, and drive current corresponding to the controlled output ofthe algorithm. In cases where the drive current serves as the controlvariable, suitable variations in drive current value should berepresented in the sets of input variables p 1218 used to train theneural network 1200. In particular, the effectiveness of drive currentas a control variable may be reduced if the training data reflectsconstant drive current values, as the neural network 1200 may reduce theweight values w 1212 associated with drive current due to its apparentlack of effect on temperature. It will be appreciated that inputvariables p 1218 other than drive current (e.g., drive voltage) may beused to minimize or reduce the difference between T_(est) and T_(th).

According to various embodiments, the generator 102 may provide power toa tissue bite according to one or more power curves. A power curve maydefine a relationship between power delivered to the tissue and theimpedance of the tissue. For example as the impedance of the tissuechanges (e.g., increases) during coagulation, the power provided by thegenerator 102 may also change (e.g., decrease) according to the appliedpower curve.

Different power curves may be particularly suited, or ill-suited, todifferent types and/or sizes of tissue bites. Aggressive power curves(e.g., power curves calling for high power levels) may be suited forlarge tissue bites. When applied to smaller tissue bites, such as smallvessels, more aggressive power curves may lead to exterior searing.Exterior searing may reduce the coagulation/weld quality at the exteriorand can also prevent complete coagulation of interior portions of thetissue. Similarly, less aggressive power curves may fail to achievehemostasis when applied to larger tissue bites (e.g., larger bundles).

FIG. 69 illustrates one embodiment of a chart 1300 showing example powercurves 1306, 1308, 1310. The chart 1300 comprises an impedance axis 1302illustrating increasing potential tissue impedances from left to right.A power axis 1304 illustrates increasing power from down to up. Each ofthe power curves 1306, 1308, 1310 may define a set of power levels, onthe power axis 1304, corresponding to a plurality of potential sensedtissue impedances, in the impedance axis 1302. In general, power curvesmay take different shapes, and this is illustrated in FIG. 69. Powercurve 1306 is shown with a step-wise shape, while power curves 1308,1310 are shown with curved shapes. It will be appreciated that powercurves utilized by various embodiments may take any usable continuous ornon-continuous shape. The rate of power delivery or aggressiveness of apower curve may be indicated by its position on the chart 1300. Forexample, power curves that deliver higher power for a given tissueimpedance may be considered more aggressive. Accordingly, between twopower curves, the curve positioned highest on the power axis 1304 may bethe more aggressive. It will be appreciated that some power curves mayoverlap.

The aggressiveness of two power curves may be compared according to anysuitable method. For example, a first power curve may be considered moreaggressive than a second power curve over a given range of potentialtissue impedances if the first power curve has a higher delivered powercorresponding to at least half of the range of potential tissueimpedances. Also, for example, a first power curve may be consideredmore aggressive than a second power curve over a given range ofpotential tissue impedances if the area under the first curve over therange is larger than the area under the second curve over the range.Equivalently, when power curves are expressed discretely, a first powercurve may be considered more aggressive than a second power curve over agiven set of potential tissue impedances if the sum of the power valuesfor the first power curve over the set of potential tissue impedances isgreater than the sum of the power values for the second power curve overthe set of potential tissue impedances.

According to various embodiments, the power curve shifting algorithmsdescribed herein may be used with any kind of surgical device (e.g.,ultrasonic device 104, electrosurgical device 106). In embodimentsutilizing a ultrasonic device 104, tissue impedance readings may betaken utilizing electrodes 157, 159. With an electrosurgical device,such as 106, tissue impedance readings may be taken utilizing first andsecond electrodes 177, 179.

In some embodiments, an electrosurgical device 104 may comprise apositive temperature coefficient (PTC) material positioned between oneor both of the electrodes 177, 179 and the tissue bite. The PTC materialmay have an impedance profile that remains relatively low and relativelyconstant until it reaches a threshold or trigger temperature, at whichpoint the impedance of the PTC material may increase. In use, the PTCmaterial may be placed in contact with the tissue while power isapplied. The trigger temperature of the PTC material may be selectedsuch that it corresponds to a tissue temperature indicating thecompletion of welding or coagulation. Accordingly, as a welding orcoagulation process is completed, the impedance of the PTC material mayincrease, bringing about a corresponding decrease in power actuallyprovided to the tissue.

It will be appreciated that during the coagulation or welding process,tissue impedance may generally increase. In some embodiments, tissueimpedance may display a sudden impedance increase indicating successfulcoagulation. The increase may be due to physiological changes in thetissue, a PTC material reaching its trigger threshold, etc., and mayoccur at any point in the coagulation process. The amount of energy thatmay be required to bring about the sudden impedance increase may berelated to the thermal mass of the tissue being acted upon. The thermalmass of any given tissue bite, in turn, may be related to the type andamount of tissue in the bite.

Various embodiments may utilize this sudden increase in tissue impedanceto select an appropriate power curve for a given tissue bite. Forexample, the generator 102 may select and apply successively moreaggressive power curves until the tissue impedance reaches an impedancethreshold indicating that the sudden increase has occurred. For example,reaching the impedance threshold may indicate that coagulation isprogressing appropriately with the currently applied power curve. Theimpedance threshold may be a tissue impedance value, a rate of change oftissue impedance, and/or a combination of impedance and rate of change.For example, the impedance threshold may be met when a certain impedancevalue and/or rate of change are observed. According to variousembodiments, different power curves may have different impedancethresholds, as described herein.

FIG. 70 illustrates one embodiment of a process flow 1330 for applyingone or more power curves to a tissue bite. Any suitable number of powercurves may be used. The power curves may be successively applied inorder of aggressiveness until one of the power curves drives the tissueto the impedance threshold. At 1332, the generator 102 may apply a firstpower curve. According to various embodiments, the first power curve maybe selected to deliver power at a relatively low rate. For example, thefirst power curve may be selected to avoid tissue searing with thesmallest and most vulnerable expected tissue bites.

The first power curve may be applied to the tissue in any suitablemanner. For example, the generator 102 may generate a drive signalimplementing the first power curve. The power curve may be implementedby modulating the power of the drive signal. The power of the drivesignal may be modulated in any suitable manner. For example, the voltageand/or current of the signal may be modulated. Also, in variousembodiments, the drive signal may be pulsed. For example, the generator102 may modulate the average power by changing the pulse width, dutycycle, etc. of the drive signal. The drive signal may be provided to thefirst and second electrodes 177, 179 of the electrosurgical device 106.Also, in some embodiments the drive signal implementing the first powercurve may be provided to an ultrasonic generator 114 of the ultrasonicdevice 104 described above.

While applying the first power curve, the generator 102 may monitor thetotal energy provided to the tissue. The impedance of the tissue may becompared to the impedance threshold at one or more energy thresholds.There may be any suitable number of energy thresholds, which may beselected according to any suitable methodology. For example, the energythresholds may be selected to correspond to known points where differenttissue types achieve the impedance threshold. At 1334, the generator 102may determine whether the total energy delivered to the tissue has metor exceeded a first energy threshold. If the total energy has not yetreached the first energy threshold, the generator 102 may continue toapply the first power curve at 1332.

If the total energy has reached the first energy threshold, thegenerator 102 may determine whether the impedance threshold has beenreached (1336). As described above, the impedance threshold may be apredetermined rate of impedance change (e.g., increase) a predeterminedimpedance, or combination of the two. If the impedance threshold isreached, the generator 102 may continue to apply the first power curveat 1332. For example, reaching the impedance threshold in the firstpower curve may indicate that the aggressiveness of the first powercurve is sufficient to bring about suitable coagulation or welding.

In the event that the impedance threshold is not reached at 1336, thegenerator 102 may increment to the next most aggressive power curve at1338 and apply the power curve as the current power curve at 1332. Whenthe next energy threshold is reached at 1334, the generator 102 againmay determine whether the impedance threshold is reached at 1336. If itis not reached, the generator 102 may again increment to the next mostaggressive power curve at 1338 and deliver that power curve at 1332.

The process flow 1330 may continue until terminated. For example, theprocess flow 1330 may be terminated when the impedance threshold isreached at 1336. Upon reaching the impedance threshold, the generator102 may apply the then-current power curve until coagulation or weldingis complete. Also, for example, the process flow 1330 may terminate uponthe exhaustion of all available power curves. Any suitable number ofpower curves may be used. If the most aggressive power curve fails todrive the tissue to the impedance threshold, the generator 102 maycontinue to apply the most aggressive power curve until the process isotherwise terminated (e.g., by a clinician or upon reaching a finalenergy threshold).

According to various embodiments, the process flow 1330 may continueuntil the occurrence of a termination threshold. The terminationthreshold may indicate that coagulation and/or welding is complete. Forexample, the termination threshold may be based on one or more of tissueimpedance, tissue temperature, tissue capacitance, tissue inductance,elapsed time, etc. These may be a single termination threshold or, invarious embodiments, different power curves may have differenttermination thresholds. According to various embodiments, differentpower curves may utilize different impedance thresholds. For example,the process flow 1330 may transition from a first to a second powercurve if the first power curve has failed to drive the tissue to a firsttissue impedance threshold and may, subsequently, shift from the secondto a third power curve if the second power curve has failed to drive thetissue to a second impedance threshold.

FIG. 71 illustrates one embodiment of a chart 1380 showing example powercurves 1382, 1384, 1386, 1388 that may be used in conjunction with theprocess flow 1330. Although four power curves 1382, 1384, 1386, 1388 areshown, it will be appreciated that any suitable number of power curvesmay be utilized. Power curve 1382 may represent the least aggressivepower curve and may be applied first. If the impedance threshold is notreached at the first energy threshold, then the generator 102 mayprovide the second power curve 1384. The other power curves 1386, 1388may be utilized, as needed, for example in the manner described above.

As illustrated in FIG. 71, the power curves 1382, 1384, 1386, 1388 areof different shapes. It will be appreciated, however, that some or allof a set of power curves implemented by the process flow 1330 may be ofthe same shape. FIG. 72 illustrates one embodiment of a chart showingexample common shape power curves 1392, 1394, 1396, 1398 that may beused in conjunction with the process flow of FIG. 70. According tovarious embodiments, common shape power curves, such as 1392, 1394,1396, 1398 may be constant multiples of one another. Accordingly, thegenerator 102 may implement the common shape power curves 1392, 1394,1396, 1398 by applying different multiples to a single power curve. Forexample, the curve 1394 may be implemented by multiplying the curve 1392by a first constant multiplier. The curve 1396 may be generated bymultiplying the curve 1392 by a second constant multiplier. Likewise,the curve 1398 may be generated by multiplying the curve 1392 by a thirdconstant multiplier. Accordingly, in various embodiments, the generator102 may increment to a next most aggressive power curve at 1338 bychanging the constant multiplier.

According to various embodiments, the process flow 1330 may beimplemented by a digital device (e.g., a processor, digital signalprocessor, field programmable gate array (FPGA), etc.) of the generator102. Examples of such digital devices include, for example, processor174, programmable logic device 166, processor 190, etc.). FIGS. 73A-73Cillustrate process flows describing routines that may be executed by adigital device of the generator 102 to generally implement the processflow 1330 described above. FIG. 73A illustrates one embodiment of aroutine 1340 for preparing the generator 102 to act upon a new tissuebite. The activation or start of the new tissue bite may be initiated at1342. At 1344, the digital device may point to a first power curve. Thefirst power curve, as described above, may be the least aggressive powercurve to be implemented as a part of the process flow 1330. Pointing tothe first power curve may comprise pointing to a deterministic formulaindicating the first power curve, pointing to a look-up tablerepresenting the first power curve, pointing to a first power curvemultiplier, etc.

At 1346, the digital device may reset an impedance threshold flag. Asdescribed below, setting the impedance threshold flag may indicate thatthe impedance threshold has been met. Accordingly, resetting the flagmay indicate that the impedance threshold has not been met, as may beappropriate at the outset of the process flow 1330. At 1348, the digitaldevice may continue to the next routine 1350.

FIG. 73B illustrates one embodiment of a routine 1350 that may beperformed by the digital device to monitor tissue impedance. At 1352,load or tissue impedance may be measured. Tissue impedance may bemeasured according to any suitable method and utilizing any suitablehardware. For example, according to various embodiments, tissueimpedance may be calculated according to Ohm's law utilizing the currentand voltage provided to the tissue. At 1354, the digital device maycalculate a rate of change of the impedance. The impedance rate ofchange may likewise be calculated according to any suitable manner. Forexample, the digital device may maintain prior values of tissueimpedance and calculate a rate of change by comparing a current tissueimpedance value or values with the prior values. Also, it will beappreciated that the routine 1350 assumes that the impedance thresholdis a rate of change. In embodiments where the impedance threshold is avalue, 1354 may be omitted. If the tissue impedance rate of change (orimpedance itself) is greater than the threshold (1356), then theimpedance threshold flag may be set. The digital device may continue tothe next routing at 1360.

FIG. 73C illustrates one embodiment of a routine 1362 that may beperformed by the digital device to provide one or more power curves to atissue bite. At 1364, power may be delivered to the tissue, for example,as described above with respect to 1334 of FIG. 70. The digital devicemay direct the delivery of the power curve, for example, by applying thepower curve to find a corresponding power for each sensed tissueimpedance, modulating the corresponding power onto a drive signalprovided to the first and second electrodes A20, A22, the transducer114, etc.

At 1366, the digital device may calculate the total accumulated energydelivered to the tissue. For example, the digital device may monitor thetotal time of power curve delivery and the power delivered at each time.Total energy may be calculated from these values. At 1368, the digitaldevice may determine whether the total energy is greater than or equalto a next energy threshold, for example, similar to the manner describedabove with respect to 1334 of FIG. 70. If the next energy threshold isnot met, the current power curve may continue to be applied at 1378 and1364.

If the next energy threshold is met at 1368, then at 1370, the digitaldevice may determine whether the impedance threshold flag is set. Thestate of the impedance threshold flag may indicate whether the impedancethreshold has been met. For example, the impedance threshold flag mayhave been set by the routine 1350 if the impedance threshold has beenmet. If the impedance flag is not set (e.g., the impedance threshold isnot met), then the digital device may determine, at 1372, whether anymore aggressive power curves remain to be implemented. If so, thedigital device may point the routine 1362 to the next, more aggressivepower curve at 1374. The routine 1362 may continue (1378) to deliverpower according to the new power curve at 1364. If all available powercurves have been applied, then the digital device may disablecalculating and checking of accumulated energy for the remainder of thetissue operation at 1376.

If the impedance flag is set at 1370 (e.g., the impedance threshold hasbeen met), then the digital device may disable calculating and checkingof accumulated energy for the remainder of the tissue operation at 1376.It will be appreciated that, in some embodiments, accumulated energycalculation may be continued, while 1370, 1372, 1374, and 1376 may bediscontinued. For example, the generator 102 and/or digital device mayimplement an automated shut-off when accumulated energy reaches apredetermined value.

FIG. 74 illustrates one embodiment of a process flow 1400 for applyingone or more power curves to a tissue bite. For example, the process flow1400 may be implemented by the generator 102 (e.g., the digital deviceof the generator 102). At 1402, the generator 102 may deliver a powercurve to the tissue. The power curve may be derived by applying amultiplier to a first power curve. At 1404, the generator 102 maydetermine if the impedance threshold has been met. If the impedancethreshold has not been met, the generator 102 may increase themultiplier as a function of the total applied energy. This may have theeffect of increasing the aggressiveness of the applied power curve. Itwill be appreciated that the multiplier may be increased periodically orcontinuously. For example, the generator 102 may check the impedancethreshold (1404) and increase the multiplier (1406) at a predeterminedperiodic interval. In various embodiments, the generator 102 maycontinuously check the impedance threshold (1404) and increase themultiplier (1406). Increasing the multiplier as a function of totalapplied energy may be accomplished in any suitable manner. For example,the generator 102 may apply a deterministic equation that receives totalreceived energy as input and provides a corresponding multiplier valueas output. Also, for example, the generator 102 may store a look-uptable that comprises a list of potential values for total applied energyand corresponding multiplier values. According to various embodiments,the generator 102 may provide a pulsed drive signal to tissue (e.g., viaone of the surgical devices 104, 106). According to various embodiments,when the impedance threshold is met, the multiplier may be heldconstant. The generator 102 may continue to apply power, for example,until a termination threshold is reached. The termination threshold maybe constant, or may depend on the final value of the multiplier.

In some embodiments utilizing a pulsed drive signal, the generator 102may apply one or more composite load curves to the drive signal, andultimately to the tissue. Composite load curves, like other power curvesdescribed herein, may define a level of power to be delivered to thetissue as a function of a measured tissue property or properties (e.g.,impedance). Composite load curves may, additionally, define pulsecharacteristics, such as pulse width, in terms of the measured tissueproperties.

FIG. 75 illustrates one embodiment of a block diagram 1450 describingthe selection and application of composite load curves by the generator102. It will be appreciated that the block diagram 1450 may beimplemented with any suitable type of generator or surgical device.According to various embodiments, the block diagram 1450 may beimplemented utilizing an electrosurgical device, such as the device 106described above with respect to FIGS. 4-7. Also, in various embodiments,the block diagram 1450 may be implemented with a ultrasonic surgicaldevice, such as the surgical device 104 described above with respect toFIGS. 2-3. In some embodiments, the block diagram 1450 may be utilizedwith a surgical device having cutting as well as coagulatingcapabilities. For example, an RF surgical device, such as the device106, may comprise a cutting edge, such as the blade 175 for severingtissue either before or during coagulation.

Referring back to FIG. 75, an algorithm 1452 may be executed, forexample by a digital device of the generator 102 to select and applycomposite load curves 1456, 1458, 1460, 1462. The algorithm 1452 mayreceive a time input from a clock 1454 and may also receive loop input1472 from sensors 1468. The loop input 1472 may represent properties orcharacteristics of the tissue that may be utilized in the algorithm 1452to select and/or apply a composite load curve. Examples of suchcharacteristics may comprise, for example, current, voltage,temperature, reflectivity, force applied to the tissue, resonantfrequency, rate of change of resonant frequency, etc. The sensors 1468may be dedicated sensors (e.g., thermometers, pressure sensors, etc.) ormay be software implemented sensors for deriving tissue characteristicsbased on other system values (e.g., for observing and/or calculatingvoltage, current, tissue temperature, etc., based on the drive signal).The algorithm 1452 may select one of the composite load curves 1456,1458, 1460, 1462 to apply, for example based on the loop input 1472and/or the time input from the clock 1454. Although four composite loadcurves are shown, it will be appreciated that any suitable number ofcomposite load curves may be used.

The algorithm 1452 may apply a selected composite load curve in anysuitable manner. For example, the algorithm 1452 may use the selectedcomposite load curve to calculate a power level and one or more pulsecharacteristics based on tissue impedance (e.g., currently measuredtissue impedance may be a part of, or may be derived from, the loopinput) or resonant frequency characteristics of a ultrasonic device 104.Examples of pulse characteristics that may be determined based on tissueimpedance according to a composite load curve may include pulse width,ramp time, and off time.

At set point 1464, the derived power and pulse characteristics may beapplied to the drive signal. In various embodiments, a feedback loop1474 may be implemented to allow for more accurate modulation of thedrive signal. At the output of the set point 1464, the drive signal maybe provided to an amplifier 1466, which may provide suitableamplification. The amplified drive signal may be provided to a load 1470(e.g., via sensors 1468). The load 1470 may comprise the tissue, thesurgical device 104, 106, and/or any cable electrically coupling thegenerator 102 with the surgical device 104, 106 (e.g., cables 112, 128).

FIG. 76 illustrates shows a process flow illustrating one embodiment ofthe algorithm 1452, as implemented by the generator 102 (e.g., by adigital device of the generator 102). The algorithm 1452 may beactivated at 1476. It will be appreciated that the algorithm 1452 may beactivated in any suitable manner. For example, the algorithm 1452 may beactivated by a clinician upon actuation of the surgical device 104, 106(e.g., by pulling or otherwise actuating a jaw closure trigger 138, 142,switch, handle, etc.).

According to various embodiments, the algorithm 1452 may comprise aplurality of regions 1478, 1480, 1482, 1484. Each region may represent adifferent stage of the cutting and coagulation of a tissue bite. Forexample, in the first region 1478, the generator 102 may perform ananalysis of initial tissue conditions (e.g., impedance). In the secondregion 1480, the generator 102 may apply energy to the tissue in orderto prepare the tissue for cutting. In the third or cut region 1482, thegenerator 102 may continue to apply energy while the surgical device104, 106 cuts the tissue (e.g., with the electrosurgical device 106,cutting may be performed by advancing the blade A18). In the fourth orcompletion region 1484, the generator 102 may apply energy post-cut tocomplete coagulation.

Referring now to the first region 1478, the generator 102 may measureany suitable tissue condition or conditions including, for example,current, voltage, temperature, reflectivity, force applied to thetissue, etc. In various embodiments, an initial impedance of the tissuemay be measured according to any suitable manner. For example, thegenerator 102 may modulate the drive signal to provide a known voltageor currency to the tissue. Impedance may be derived from the knownvoltage and the measured current or vice versa. It will be appreciatedthat tissue impedance may alternately or additionally be measured in anyother suitable manner. According to the algorithm 1452, the generator102 may proceed from the first region 1478 to the second region 1480. Invarious embodiments, the clinician may end the algorithm 1452 in thefirst region 1478, for example, by deactivating the generator 102 and/orthe surgical device 104, 106. If the clinician terminates the algorithm1542, RF (and/or ultrasonic) delivery may also be terminated at 1486.

In the second region 1480, the generator 102 may begin to apply energyto the tissue via the drive signal to prepare the tissue for cutting.Energy may be applied according to the composite load curves 1456, 1458,1460, 1462, as described below. Applying energy according to the secondregion 1480 may comprise modulating pulses onto the drive signalaccording to some or all of the composite load curves 1456, 1458, 1460,1462. In various embodiments, the composite load curves 1456, 1458,1460, 1462 may be successively applied in order of aggressiveness (e.g.,to accommodate various types of tissue-volume clamped in the instrumentjaws).

The first composite load curve 1456 may be applied first. The generator102 may apply the first composite load curve 1456 by modulating one ormore first composite load curve pulses onto the drive signal. Each firstcomposite load curve pulse may have a power and pulse characteristicsdetermined according to the first composite load curve and consideringmeasured tissue impedance. Measured tissue impedance for the first pulsemay be the impedance measured at the first region 1478. In variousembodiments, the generator 102 may utilize all or a portion of the firstcomposite load curve pulses to take additional measurements of tissueimpedance or resonant frequency. The additional measurements may be usedto determine the power and other pulse characteristics of a subsequentpulse or pulses.

FIG. 77 illustrates one embodiment of a process flow 1488 for generatinga first composite load curve pulse. The process flow 1488 may beexecuted by the generator 102 (e.g., by a digital device of thegenerator 102), for example, as a part of the algorithm 1452. At 1490,the generator 102 may calculate a pulse width (T_(pw)). The pulse widthmay be determined considering the most recent measured tissue impedance(Z) and according to the first composite load curve 1456.

At 1492, the generator 102 may ramp the power of the drive signal up toa pulse power (PLimit) over a ramp time (t_(ramp)), thereby applying thepulse to the tissue. The pulse power may be determined, again,considering the most recent measured tissue impedance (Z) and accordingto the first composite load curve 1456. The ramp time may be determinedaccording to the composite load curve considering tissue impedance ormay be constant (e.g., constant for all first composite load curvepulses, constant for all pulses, etc.). The generator 102 may apply thepulse power to the drive signal in any suitable manner including, forexample, modulating a current and/or voltage provided by the drivesignal. According to various embodiments, the drive signal may be analternating current (A/C) signal, and therefore the pulse itself maycomprise multiple cycles of the drive signal.

The drive signal may be held at the pulse power for the pulse width at1494. At the conclusion of the pulse, the drive signal may be rampeddown, at 1496, over a fall time (T_(fail)). The fall time may bedetermined according to the first composite load curve consideringtissue impedance, or may be constant (e.g., constant for all firstcomposite load curve pulses, constant for all pulses, etc.). It will beappreciated that, depending on the embodiment, the ramp time and falltime may or may not be considered part of the pulse width. At 1498, thegenerator 102 may pause for an off time (T_(off)). Like the ramp timeand fall time, the off time may be determined according to the firstcomposite load curve considering tissue impedance, or may be constant(e.g., constant for all first composite load curve pulses, constant forall pulses, etc.).

At the completion of the off time, the generator 102 may repeat theprocess flow 1488 as long as the first composite load curve 1456 isapplied. According to various embodiments, the generator 102 may applythe first composite load curve 1456 for a predetermined amount of time.Accordingly, the process flow 1488 may be repeated until thepredetermined amount of time has elapsed (e.g., as determined based onthe time input received from the clock 1454). Also, in variousembodiments, the first composite load curve may be applied for apredetermined number of pulses. Because the applied pulse width variesaccording to measured tissue impedance, the total time that the firstcomposite load curve is applied may also vary with measured tissueimpedance. According to various embodiments, the first composite loadcurve 1456 (as well as the other composite load curves 1458, 1460, 1462)may specify decreasing pulse widths as tissue impedance increases.Therefore, a higher initial tissue impedance may lead to less time spentin the first composite load curve.

Upon completion of the first composite load curve 1456, the generator102 may successively apply the remaining consolidated load curves 1458,1460, 1462 throughout the application of the second region 1480. Eachload curve 1458, 1460, 1462 may be applied in a manner similar to thatof the load curve 1456 described above. For example, pulses according toa current load curve may be generated until the completion of that loadcurve (e.g., the expiration of a predetermined amount of time or apredetermined number of pulses). The predetermined number of pulses maybe the same for each composite load curve 1456, 1458, 1460, 1462 or maybe different. According to various embodiments, pulses according to theload curves 1458, 1460, 1462 may be generated in a manner similar toprocess flow 1488, except that pulse power, pulse width and, in someembodiments, ramp time, fall time, and off time, may be derivedaccording to the current composite load curve.

The second region 1480 may be terminated upon the occurrence of variousevents. For example, if the total RF application time has exceeded atimeout time, then the generator 102 may end the tissue operation byterminating RF (and/or ultrasonic) delivery at 1486. Also, variousevents may cause the generator 102 to transition from the second region1480 to the third region 1482. For example, the generator 102 maytransition to the third region 1482 when the tissue impedance (Z)exceeds a threshold tissue impedance (Z_(term)) and RF energy has beendelivered for at least more than a minimum time (T_(start)). Thethreshold tissue impedance may be an impedance and/or an impedance rateof change indicating that the tissue bite is adequately prepared forcutting by the blade 175.

According to various embodiments, if the final load curve 1462 iscompleted in the second region 1480 before completion of the secondregion 1480, then the final power curve 1462 may be continuouslyapplied, for example, until the tissue impedance threshold is met, themaximum second region time is reached and/or the timeout time isreached. Also, it will be appreciated that, with some tissue cuts, thesecond region 1480 may be completed before all available consolidatedload curves 1456, 1458, 1460, 1462 are executed.

At the third region 1482, the generator 102 may continue to modulatepulses onto the drive signal. Generally, third region pulses may bemodulated onto the drive signal according to any suitable mannerincluding, for example, that described above with reference to theprocess flow 1488. The power and pulse characteristics of the thirdregion pulses may be determined according to any suitable method and, invarious embodiments, may be determined based on the composite load curvethat was being executed at the completion of the second region 1480 (thecurrent load curve). According to various embodiments, the current loadcurve may be utilized to determine the pulse power of third regionpulses, while the pulse characteristics (e.g., pulse width, ramp time,fall time, off time, etc.) may be constant regardless of composite loadcurve. In some embodiments, the third region 1482 may utilize athird-region-specific composite load curve that may be one of the loadcurves 1456, 1458, 1460, 1462 utilized in the second region 1480, or maybe a different composite load curve (not shown).

The generator 102 may continue to execute the third region 1482 untilreceiving an indication that the tissue cut is complete. In embodimentsutilizing surgical implements having a blade, such as 175, theindication may be received when the blade 175 reaches its distal-mostposition, as shown in FIG. 6. This may trip a knife limit sensor (notshown) indicating that the blade 175 has reached the end of its throw.Upon receiving the indication that the tissue cut is complete, thegenerator 102 may continue to the fourth region 1484. It will also beappreciated that, in some embodiments, the generator 102 may transitionfrom the third region 1482 directly to RF (and/or ultrasonic)termination at 1486, for example, if the timeout time has been reached.

In the fourth region 1484, the generator 102 may provide an energyprofile designed to complete coagulation of the now-cut tissue. Forexample, according to various embodiments, the generator 102 may providea predetermined number of pulses. The pulses may be provided in a mannersimilar to that described above with respect to the process flow 1488.The power and pulse characteristics of the pulses may be determinedaccording to any suitable manner. For example, power and pulsecharacteristics of the fourth region pulses may be determined based onthe current composite load curve, the third-region-specific load curve,or a fourth-region-specific composite load curve. In some embodiments,power may be determined based on the current composite load curve, whilepulse characteristics may be fourth region-specific. Also, according tovarious embodiments, the power and pulse characteristics of fourthregion pulses may be determined independent of the current compositeload curve.

FIG. 78 illustrates one embodiment of a pulse timing diagram 1474illustrating an example application of the algorithm 1452 by thegenerator 102 (e.g., by a digital device of the generator 102). A firstregion pulse 1502 is shown in the first region 1478. The first regionpulse 1502 may be utilized, as described, to measure an initial tissueimpedance. At the completion of the first region pulse (1509), secondregion 1480 may begin with second region pulses 1504 applied. The secondregion pulses 1504 may be applied according to the various compositeload curves 1456, 1458, 1460, 1462, for example, as described herein. Inthe example diagram 1474, the second region 1480 concludes at 1510 whenthe tissue reaches the threshold impedance (Z_(term)). The third region1482 is then implemented, with third region pulses 1506, as describedabove, applied until a knife limit signal is received at 1512. At thatpoint, the fourth region 1484 may commence, with fourth region pulses1508, as described above, applied until cycle completion at 1514.

According to various embodiments, the generator 102 may implement a userinterface in conjunction with the algorithm 1452. For example, the userinterface may indicate the current region of the algorithm. The userinterface may be implemented visually and/or audibly. For example, thegenerator 102 may comprise a speaker for generating audible tones orother audible indication. At least one audible indication may correspondto the second region 1480. The third and fourth regions 1482, 1484 mayalso have region-specific audible indications. According to variousembodiments, the first region 1478 may have a region-specific audibleindication as well. According to various embodiments, the audibleindications may comprise pulsed tones generated by the generator 102.The frequency of the tones and/or the pitch of the tones themselves mayindicate the current region. In addition to, or instead of, the audibleindications, the generator 102 may also provide a visual indication ofthe current region (e.g., on output device 147). It will be appreciatedthat the clinician may utilize the described user interface to properlyuse the generator 102 and associated surgical devices 104, 106. Forexample, the indication of the second region 1480 may let the clinicianknow that tissue treatment has begun. The indication of the third region1482 may let the clinician know that the tissue is ready for the cuttingoperation. The indication of the fourth region 1484 may let theclinician know that the cutting operation is complete. The cessation ofthe indication and/or a final indication may indicate that the totalcutting/coagulation operation is complete.

FIG. 79 illustrates a graphical representation of drive signal voltage,current and power according to an example load curve 1520. In the chart1520, drive signal voltage is represented by line 1522, drive signalcurrent is represented by line 1524 and drive signal power isrepresented by line 1526. Pulse width is not indicated in FIG. 79. Invarious embodiments, the values for voltage 1522, current 1524 and power1526 indicated by the graph 1520 may represent possible values within asingle pulse. Accordingly, the load curve 1520 may be expressed as acomposite load curve by adding a curve (not shown) indicating a pulsewidth as a function of tissue impedance or another tissue condition. Asshown for the load curve 1520, the maximum voltage 1522 is 100 VoltsRoot Mean Square (RMS), the maximum current is 3 Amps RMS and themaximum power is 135 Watts RMS.

FIGS. 79-84 illustrate graphical representations of various examplecomposite load curves 1530, 1532, 1534, 1536, 1538, 1540. Each of thecomposite load curves 1530, 1532, 1534, 1536, 1538, 1540 may indicateboth pulse power and pulse width in terms of measured tissue impedance.The composite load curves 1530, 1532, 1534, 1536 may be implementedeither in isolation or as part of a pattern of successively moreaggressive composite load curves, as described above with respect to thealgorithm 1452.

FIG. 80 illustrates a graphical representation of a first examplecomposite load curve 1530. The composite load curve 1530 may have amaximum pulse power of 45 Watts RMS and a maximum pulse width of 0.35seconds. In FIG. 80, the power as a function of tissue impedance isindicated by 1542, while the pulse width as a function of tissueimpedance is indicated by 1544. Table 1 below illustrates values for thecomposite load curve 1530 for tissue impedances from 0Ω to 475Ω.

TABLE 1 Load, V Lim, I Lim, P Lim, PW, Ohms RMS RMS W Sec   0-24 85 1.445 0.35  25-49 85 1.4 45 0.35  50-74 85 1.4 45 0.3  75-99 85 1.4 45 0.3100-124 85 1.4 45 0.25 125-149 85 1.4 45 0.25 150-174 85 1.4 45 0.2175-199 85 1.4 45 0.2 200-224 85 1.4 44 0.15 225-249 85 1.4 40 0.15250-274 85 1.4 36 0.1 275-299 85 0.31 24 0.1 300-324 85 0.28 22 0.1325-349 85 0.26 20 0.1 350-374 85 0.25 19 0.1 375-399 85 0.22 18 0.1400-424 85 0.21 17 0.1 425-449 85 0.2 16 0.1 450-475 85 0.19 15 0.1 475+85 0.15 14 0.1In various embodiments, the composite load curve 1530 may be suited tosmaller surgical devices and/or smaller tissue bites.

FIG. 81 illustrates a graphical representation of a second examplecomposite load curve 1532. The composite load curve 1532 may have amaximum pulse power of 45 Watts RMS and a maximum pulse width of 0.5seconds. In FIG. 81, the power as a function of tissue impedance isindicated by 1546, while the pulse width as a function of tissueimpedance is indicated by 1548. Table 2 below illustrates values for thecomposite load curve 1532 for tissue impedances from 0Ω to 475Ω.

TABLE 2 Load, V Lim, I Lim, P Lim, PW, Ohms RMS RMS W Sec   0-24 85 3 450.5  25-49 85 2 45 0.5  50-74 85 1.4 45 0.5  75-99 85 1.1 45 0.5 100-12485 0.9 45 0.5 125-149 85 0.7 45 0.5 150-174 85 0.55 45 0.5 175-199 850.48 45 0.5 200-224 85 0.42 32 0.5 225-249 85 0.38 28 0.5 250-274 850.33 26 0.3 275-299 85 0.31 24 0.3 300-324 85 0.28 22 0.25 325-349 850.26 20 0.25 350-374 85 0.25 19 0.25 375-399 85 0.22 18 0.25 400-424 850.21 17 0.25 425-449 85 0.2 16 0.25 450-475 85 0.19 15 0.25 475+ 85 0.1514 0.25The composite load curve 1532 may be targeted at small, single vesseltissue bites and, according to various embodiments, may be a firstcomposite power curve applied in region two 1480.

FIG. 82 illustrates a graphical representation of a third examplecomposite load curve 1534. The composite load curve 1534 may have amaximum pulse power of 60 Watts RMS and a maximum pulse width of 2seconds. In FIG. 82, the power as a function of tissue impedance isindicated by 1550, while the pulse width as a function of tissueimpedance is indicated by 1552. Table 3 below illustrates values for thecomposite load curve 1534 for tissue impedances from 0Ω to 475Ω.

TABLE 3 Load, V Lim, I Lim, P Lim, PW, Ohms RMS RMS W Sec   0-24 85 3 602  25-49 85 3 60 2  50-74 100 3 60 2  75-99 100 3 60 2 100-124 100 3 602 125-149 100 3 60 2 150-174 100 3 55 0.5 175-199 100 3 50 0.5 200-22485 0.42 32 0.3 225-249 85 0.38 28 0.3 250-274 85 0.33 26 0.3 275-299 850.31 24 0.3 300-324 85 0.28 22 0.25 325-349 85 0.26 20 0.25 350-374 850.25 19 0.25 375-399 85 0.22 18 0.25 400-424 85 0.21 17 0.25 425-449 850.2 16 0.25 450-475 85 0.19 15 0.25 475+ 85 0.15 14 0.25The composite load curve 1534 may be more aggressive than the priorcurve 1532 by virtue of its generally higher power. The composite loadcurve 1534 may also, initially, have higher pulse widths than the priorcurve 1532, although the pulse widths of the composite load curve 1534may begin to drop at just 150Ω. According to various embodiments, thecomposite load curve 1536 may be utilized in the algorithm 1542 as aload curve implemented sequentially after the composite load curve 1532.

FIG. 83 illustrates a graphical representation of a fourth examplecomposite load curve 1536. The composite load curve 1536 may have amaximum pulse power of 90 Watts RMS and a maximum pulse width of 2seconds. In FIG. 83, the power as a function of tissue impedance isindicated by 1554, while the pulse width as a function of tissueimpedance is indicated by 1556. Table 4 below illustrates values for thecomposite load curve 1536 for tissue impedances from 0Ω to 475Ω.

TABLE 4 Load, V Lim, I Lim, P Lim, PW, Ohms RMS RMS W Sec   0-24 85 3 902  25-49 85 3 90 2  50-74 100 3 90 2  75-99 100 3 90 2 100-124 100 3 802 125-149 100 3 65 2 150-174 100 3 55 0.5 175-199 100 3 50 0.5 200-22485 0.42 32 0.3 225-249 85 0.38 28 0.3 250-274 85 0.33 26 0.3 275-299 850.31 24 0.3 300-324 85 0.28 22 0.25 325-349 85 0.26 20 0.25 350-374 850.25 19 0.25 375-399 85 0.22 18 0.25 400-424 85 0.21 17 0.25 425-449 850.2 16 0.25 450-475 85 0.19 15 0.25 475+ 85 0.15 14 0.25The composite load curve 1536 may, again, be more aggressive than theprior curve 1534 and, therefore, may be implemented sequentially afterthe curve 1534 in the algorithm 1452. Also, according to variousembodiments, the composite load curve 1536 maybe suited to larger tissuebundles.

FIG. 84 illustrates a graphical representation of a fifth examplecomposite load curve 1538. The composite load curve 1538 may have amaximum pulse power of 135 Watts RMS and a maximum pulse width of 2seconds. In FIG. 84, the power as a function of tissue impedance isindicated by 1558, while the pulse width as a function of tissueimpedance is indicated by 1560. Table 5 below illustrates values for thecomposite load curve 1538 for tissue impedances from 0Ω to 475Ω.

TABLE 5 Load, V Lim, I Lim, P Lim, PW, Ohms RMS RMS W Sec   0-24 85 3135 2  25-49 85 3 135 2  50-74 100 3 135 2  75-99 100 3 100 2 100-124100 3 80 2 125-149 100 3 65 2 150-174 100 3 55 0.5 175-199 100 3 50 0.5200-224 85 0.42 32 0.3 225-249 85 0.38 28 0.3 250-274 85 0.33 26 0.3275-299 85 0.31 24 0.3 300-324 85 0.28 22 0.25 325-349 85 0.26 20 0.25350-374 85 0.25 19 0.25 375-399 85 0.22 18 0.25 400-424 85 0.21 17 0.25425-449 85 0.2 16 0.25 450-475 85 0.19 15 0.25 475+ 85 0.15 14 0.25The composite load curve 1538 may be used sequentially after the priorcurve 1536 in the algorithm 1452.

FIG. 85 illustrates a graphical representation of a sixth examplecomposite load curve 1540. The composite load curve 1540 may have amaximum pulse power of 90 Watts RMS and a maximum pulse width of 2seconds. In FIG. 85, the power as a function of tissue impedance isindicated by 1562, while the pulse width as a function of tissueimpedance is indicated by 1564. Table 6 below illustrates values for thecomposite load curve 1540 for tissue impedances from 0Ω to 475Ω.

TABLE 6 Load, V Lim, I Lim, P Lim, PW, Ohms RMS RMS W Sec   0-24 85 3 902  25-49 85 3 90 2  50-74 100 3 90 2  75-99 100 3 90 2 100-124 100 3 802 125-149 100 3 65 2 150-174 100 3 55 0.5 175-199 100 3 50 0.5 200-22485 0.42 32 0.3 225-249 85 0.38 28 0.3 250-274 85 0.33 26 0.3 275-299 850.31 24 0.3 300-324 85 0.28 22 0.25 325-349 85 0.26 20 0.25 350-374 850.25 19 0.25 375-399 85 0.22 18 0.25 400-424 85 0.21 17 0.25 425-449 850.2 16 0.25 450-475 85 0.19 15 0.25 475+ 85 0.15 14 0.25The composite power curve 1540 is less aggressive than the prior powercurve 1538. According to various embodiments, the composite power curve1540 may be implemented in the algorithm 1452 sequentially after thecurve 1538. Also, in some embodiments, the composite power curve 1540may be implemented in the algorithm 1452 as a third or fourthregion-specific composite power curve.

As described above, the various composite power curves used in thealgorithm 1452 may each be implemented for a predetermined number ofpulses. Table 7 below illustrates the number of pulses per compositepower curve for an example embodiment utilizing the power curves 1532,1534, 1536, 1540 sequentially in the algorithm 1452.

TABLE 7 Composite Load Curve Number of Pulses 1532 4 1534 2 1536 2 15388 1540 n/aThe last composite power curve 1540 is shown without a correspondingnumber of pulses. For example, the composite power curve 1540 may beimplemented until the clinician terminates the operation, until thetimeout time is reached, until the threshold tissue impedance isreached, etc.

According to various embodiments, the generator 102 may provide power toa tissue bite in a manner that brings about a desired value of othertissue parameters. FIG. 86 illustrates one embodiment of a block diagram1570 describing the application of an algorithm 1572 for maintaining aconstant tissue impedance rate of change. The algorithm 1572 may beimplemented by the generator 102 (e.g., by a digital device of thegenerator 102). For example, the algorithm 1572 may be utilized by thegenerator 102 to modulate the drive signal. Sensors 1574 may sense atissue condition, such as tissue impedance and/or a rate of change oftissue impedance. The sensors 1574 may be hardware sensors or, invarious embodiments may be software implemented sensors. For example,the sensors 1574 may calculate tissue impedance based on measured drivesignal current and voltage. The drive signal may be provided by thegenerator 102 to the cable/implement/load 1576, which may be theelectrical combination of the tissue, the surgical device 104, 106 and acable 112, 128 electrically coupling the generator 102 to the device104, 106.

The generator 102, by implementing the algorithm 1572, may monitor theimpedance of the tissue or load including, for example, the rate ofchange of impedance. The generator 102 may modulate one or more of thevoltage, current and/or power provided via the drive signal to maintainthe rate of change of tissue impedance at a predetermined constantvalue. Also, according to various embodiments, the generator 102 maymaintain the rate of change of the tissue impedance at above a minimumimpedance rate of change.

It will be appreciated that the algorithm 1572 may be implemented inconjunction with various other algorithms described herein. For example,according to various embodiments, the generator 102 may sequentiallymodulate the tissue impedance to different, increasingly aggressiverates similar to the method 1330 described herein with reference to FIG.70 herein. For example, a first impedance rate of change may bemaintained until the total energy delivered to the tissue exceeds apredetermined energy threshold. At the energy threshold, if tissueconditions have not reached a predetermined level (e.g., a predeterminedtissue impedance), then the generator 102 may utilize the drive signalto drive the tissue to a second, higher impedance rate of change. Also,in various embodiments, tissue impedance rates of change may be used ina manner similar to that described above with respect to composite loadcurves. For example, instead of utilizing plurality of composite loadcurves, the algorithm 1452 of FIG. 75 may call for applying a pluralityof rates of tissue impedance change. Each rate of tissue impedancechange may be maintained for a predetermined amount of time and/or apredetermined number of pulses. The rates may be successively applied inorder of value (e.g., rates may successively increase). In someembodiments, however, the driven rates of tissue impedance change maypeak, and then be reduced.

Although the various embodiments of the devices have been describedherein in connection with certain disclosed embodiments, manymodifications and variations to those embodiments may be implemented.For example, different types of end effectors may be employed. Also,where materials are disclosed for certain components, other materialsmay be used. The foregoing description and following claims are intendedto cover all such modification and variations.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

1. A surgical generator for providing a drive signal to a surgical device, the generator comprising: a first transformer comprising a first primary winding and a first secondary winding; a second transformer comprising a second primary winding and a second secondary winding; a generator circuit to generate the drive signal, wherein the generator circuit is electrically coupled to the first primary winding to provide the drive signal across the first primary winding; a patient-side circuit electrically isolated from the generator circuit, wherein the patient-side circuit is electrically coupled to the first secondary winding, and wherein the patient-side circuit comprises first and second output lines to provide the drive signal to the surgical device; and a capacitor, wherein the capacitor and the second secondary winding are electrically coupled in series between the first output line and ground.
 2. The surgical generator of claim 1, wherein the capacitor has a first electrode electrically coupled to the first output line and a second electrode electrically coupled to the second secondary winding.
 3. The surgical generator of claim 2, wherein the second secondary winding comprises a first electrode electrically coupled to the second electrode of the capacitor and a second electrode electrically coupled to ground.
 4. The surgical generator of claim 3, wherein the load resistor has a first electrode electrically coupled to the first electrode of the second secondary winding and a second electrode electrically coupled to the second electrode of the second secondary winding.
 5. The surgical generator of claim 1, wherein the second secondary winding comprises a first electrode electrically coupled to the first output line and a second electrode electrically coupled to the capacitor.
 6. The surgical generator of claim 1, wherein the capacitor comprises a first electrode electrically coupled to the second electrode of the second secondary winding and a second electrode electrically coupled to ground.
 7. The surgical generator of claim 1, further comprising: a correction circuit positioned in series between the capacitor and ground; and a correction control circuit, wherein the correction circuit is programmed to: receive input describing at least one of a current of the drive signal, a voltage of the drive signal and a load condition describing a property of tissue acted upon by the drive signal; calculate a correction signal; and provide the correction signal to the correction circuit;
 8. The surgical generator of claim 7, wherein the correction control circuit comprises: at least one processor; at least one analog-to-digital converter to convert the input to digital; and at least one digital-to-analog converter to convert the correction signal to analog.
 9. The surgical generator of claim 1, wherein the capacitor is a Y-type capacitor.
 10. The surgical generator of claim 1, further comprising a load resistor electrically coupled in parallel with the second secondary winding, wherein a polarity of the second secondary winding relative to second primary winding is opposite of a polarity of the first secondary winding.
 11. A surgical generator for providing a drive signal to a surgical device, the generator comprising: a first transformer comprising a primary winding, a first secondary winding, and a second secondary winding, wherein a polarity of the first secondary winding relative to the primary winding is opposite the polarity of the second secondary winding; a generator circuit to generate the drive signal, wherein the generator circuit is electrically coupled to the first primary winding to provide the drive signal across the first primary winding; a patient-side circuit electrically isolated from the generator circuit, wherein the patient-side circuit is electrically coupled to the first secondary winding, and wherein the patient-side circuit comprises first and second output lines to provide the drive signal to the surgical device; and a capacitor, wherein the capacitor and second secondary winding are electrically coupled in series between the first output line and ground.
 12. The surgical generator of claim 11, wherein the capacitor has a first electrode electrically coupled to the first output line and a second electrode electrically coupled to the second secondary winding.
 13. The surgical generator of claim 12, wherein the second secondary winding comprises a first electrode electrically coupled to the second electrode of the capacitor and a second electrode electrically coupled to ground.
 14. The surgical generator of claim 13, further comprising a load resistor electrically coupled in parallel with the second secondary winding, wherein the load resistor has a first electrode electrically coupled to the first electrode of the second secondary winding and a second electrode electrically coupled to the second electrode of the second secondary winding.
 15. The surgical generator of claim 11, wherein the second secondary winding comprises a first electrode electrically coupled to the first output line and a second electrode electrically coupled to the capacitor.
 16. The surgical generator of claim 11, wherein the capacitor comprises a first electrode electrically coupled to the second electrode of the second secondary winding and a second electrode electrically coupled to ground.
 17. The surgical generator of claim 11, further comprising: a correction control circuit positioned in series between the capacitor and ground; and a correction control circuit, wherein the correction circuit is programmed to: receive input describing at least one of a current of the drive signal, a voltage of the drive signal and a load condition describing a property of tissue acted upon by the drive signal; calculate a correction signal; and provide the correction signal to the correction circuit;
 18. The surgical generator of claim 17, wherein the correction control circuit comprises: at least one processor; at least one analog-to-digital converter to convert the input to digital; and at least one digital-to-analog converter to convert the correction signal to analog.
 19. The surgical generator of claim 11, wherein the capacitor is a Y-type capacitor.
 20. A surgical generator for providing a drive signal to a surgical device, the generator comprising: a first transformer comprising a primary winding and a secondary winding; a generator circuit to generate the drive signal, wherein the generator circuit is electrically coupled to the first primary winding to provide the drive signal across the first primary winding; a patient-side circuit electrically isolated from the generator circuit, wherein the patient-side circuit is electrically coupled to the secondary winding, and wherein the patient-side circuit comprises first and second output lines to provide the drive signal to the surgical device; a capacitor, wherein the capacitor and is electrically coupled to the primary winding and electrically coupled to the first output line.
 21. The surgical generator of claim 20, wherein the capacitor is a Y-type capacitor.
 22. A surgical generator for providing a drive signal to a surgical device, the generator comprising: a first transformer comprising a primary winding and a secondary winding; a generator circuit to generate the drive signal, wherein the generator circuit is electrically coupled to the first primary winding to provide the drive signal across the first primary winding; a patient-side circuit electrically isolated from the generator circuit, wherein the patient-side circuit is electrically coupled to the secondary winding, and wherein the patient-side circuit comprises first and second output lines to provide the drive signal to the surgical device; a first capacitor, wherein a first electrode of the first capacitor and is electrically coupled to the primary winding; a second capacitor, wherein a first electrode of the second capacitor is electrically coupled to the first output line and a second electrode of the second capacitor is electrically coupled to a second electrode of the first capacitor; a third capacitor, wherein the a first electrode of the third capacitor is electrically coupled to the second electrode of the first capacitor and the second electrode of the second capacitor, and wherein a second electrode of the third capacitor is electrically coupled to ground.
 23. The surgical generator of claim 22, wherein the second capacitor is a Y-type capacitor. 